Tens of thousands of pro-Palestinian protesters massed in Washington, DC, Saturday afternoon before descending upon the White House to chant, “Allahu akbar” and “F–k Joe Biden” as they accused the president of genocide and demanded a ceasefire in the Gaza Strip.

“From the river to the sea, Palestine will be free,” the crowd dotted with Palestinian flags and signs cried at the start of the event, which drew attendees from across the country.

The chant – which is growing increasingly popular in the wake of Hamas’ deadly incursion into southern Israel last month and Israel’s subsequent retaliatory attacks on Gaza – is widely considered antisemitic because it implies the elimination of the State of Israel and its people.

Others chanted, “Long live the Intifada,” an Arabic word used to refer to Palestinian uprising, specifically to conflicts that ran from 1987 and 1993 and from 2000 to about 2005 that left thousands dead.

Unofficial reports estimate more than 100,000 showed up to the protest, but DC Police could not confirm, telling The Post it does not estimate crowd size. 

One man was arrested for destruction of property around 5:30 p.m., according to DC cops. It is unclear what he was destroying. 

As the protesters began marching down the roadways of DC, many stopped outside the White House to yell for Biden to call for a ceasefire. Biden was at his Rehoboth Beach, Del., vacation home. 

Around 6:30 p.m., protesters were smearing red paint on the gates of the White House and chanting: “Allahu akbar,” “F–k Joe Biden,” a Post reporter observed. 

One demonstrator even scaled the security fence around the Executive Mansion to wave a Palestinian flag, X video showed.

DC Police have been circling the White House via helicopter, according to an X user. 

The tens of thousands of protesters — including rapper Macklemore — could be seen for miles as their roarous chants filled the streets since around 1 p.m. 

Earlier in the day, an Israeli supporter — who was seen walking the streets with the country’s flag around his shoulders — was politely escorted away by police, according to the X poster. 

The Post reporter said the protest was unlike any other he had ever witnessed.

“This one was distinguished by the defacing of the gate and pushing on it, chants of ‘Allahu akbar’ and thousands of Muslims, leftists and others chanting against Biden,” he said. “It was remarkable that it ended peacefully. (With) many families in the fired-up crowd, it could have been bad.

“When gates were swaying tonight, one protester said to me, ‘It’s going to be all over’ if they were to open,” he added. “In the moment, it wasn’t hard to imagine hundreds going through the gate.”

Although the movement was mostly peaceful, several vandals seized the opportunity to deface the outside gate of the Executive Mansion with red paint, smothering the white brick with blood-like hand prints.

Protesters also shattered the windows of a nearby McDonald’s, which was already peppered with pro-Palestinian stickers and spray paint.

While the protest took shape in the nation’s capital, more than 1,000 pro-Palestinian demonstrators blocked traffic in Manhattan’s Herald Square, demanding a ceasefire, before the throng moved east to the United Nations, where the crowd swelled to 2,000, police sources told The Post.

There were no incidents or arrests before the crowd dispersed without incident or arrests around 7:30 p.m., the sources said.

Other protests around the world have broken out as well, including in London where at least 11 people were arrested by Metropolitan Police for various things, including holding signs threatening to burn down the House of Parliament. 

In Washington, speakers from several organizations took the stage to encourage the crowd’s “righteous anger” in response to the deaths of around 9,000 Palestinians in Gaza since the Israeli airstrikes began following the horrific Oct. 7 attacks on Southern Israel.

Many of the speakers touched on the US role as Israel’s primary ally in the ongoing war against Hamas – including a $14.3 billion aid package passed by the House this week.

“Biden, Biden you can’t hide! We charge you with genocide!” one MC yelled into the microphone, drawing cheers from the attendees.

Several demonstrators who claimed to work for the Biden administration and members of Congress joined the protest, holding signs saying: “Congress your staff demand a ceasefire” and “Biden your staff demand a ceasefire.”

A spokesperson for the Chicago Chapter of the US Palestine Community Network said Biden was “dehumanizing” Palestinians.

“No business as usual as our elected officials support genocide,” she yelled into the microphone.

“Israel does not have the right to exist as a racist state.”

The speaker said Palestinians wanted to build a “secular” society “from the river to the sea” afterward.

“It is right to rebel! Israel can go to hell!” Marte White, who said he was from Community Movement Builders, a nationwide black activist group, yelled during his turn at the mic.

Palestinians have a right to fight “by any means necessary…and I do mean any means necessary!” White said, presumably referring to Hamas slaughtering and maiming 1,400 Israelis within a few hours on Oct. 7.

“Everyone should support the struggle against Zionism, and stand with the Palestinian people,” White concluded.

After White’s particularly fiery rhetoric, the MCs requested a moment of silence for the “martyrs” killed in Gaza over the last four weeks.

At that point, a white tarp was unfurled over part of the crowd in a silent call for peace.

The moment of silence was followed by Dr. Omar Suleiman referring to the Israeli government as “apartheid” as he touched on violence against Palestinian youth in Gaza, the West Bank, and beyond – including the six-year-old Chicago boy who was stabbed by his landlord.

“Know that when [people] say they ‘stand with Israel,’ they are saying they ‘stand with genocide,’” he said.

“This has been one of the hardest months in my lifetime – and I’m the post-Oslo [Accords] generation,” a speaker from the Palestinian Youth Movement said, referring to the 1993 pact brokered by the Clinton Administration.

“This has been one of the hardest months in history, for our people.”

“We have a deep conviction that Palestine will be free in our lifetime,” she insisted. “This is 75 years of justice deferred! We are demanding a stop to all [US] aid to the Zionist state of Israel!”

The crowd eventually grew so large that one portion of the group was asked to move over to allow another wave to join from around the corner.

The Palestinian national anthem was played over loudspeakers from the stage while the maneuvering took place.

Despite the frequent antisemitic tone from the speakers, one woman, Ahlam, from Maryland2Palestine, insisted that “righteous anger is not hate, it’s love.”

“We should be angry when it’s our money going to fund these entities,” she said of the US and corporations’ support of Israel’s efforts to defeat Hamas.

Ahlam called for a continued boycott of companies like Starbucks and McDonald’s that have expressed solidarity with Israel.

“We will not get our names written on Starbucks cups while Palestinian children are writing their names on their arms so that their bodies may be identified after an airstrike!” she cried.

The massive protest ended almost as abruptly as it began, with the crowd of thousands mostly dissipated by 8 p.m.

“They saw me coming,” a Secret Service officer joked.

Activists left behind some signs and stickers affixed to the fence for President Biden.

— Additional reporting by Katherine Donlevy