Thousands of anti-Israel protesters Monday flooded Manhattan’s streets on the first anniversary of the Oct. 7 terror attack — spewing hate-fueled slogans as some launched a violent attack on a Jewish leader.

The largely anti-Israel mobs amassed end to end — from Columbia University to Wall Street — with the expected unrest telegraphed early on when antisemitic vandals struck at an uptown CUNY campus, smashing windows on a building and scrawling an anti-Israel message in red paint across it.

At Columbia, a hotbed of antisemitic hate since the massacre, a large crowd chanted, “Resistance is glorious!”

On Wall Street, the founder of the anti-Israel group Within Our Lifetime, Nerdeen Kiswani, addressed a crowd of hundreds, saying, “We are going to flood New York City — for all of Gaza, for all of Yemen, for all of Lebanon” — three regions where terror groups have been launching attacks on Israel.

The crowd chanted, “Israel bombs, USA pays, how many kids did you kill today?” “From the river to the sea, Palestine will be free,” and, “No cops, no KKK, no fascist USA.”

City Councilman Robert Holden (D-Queens) denounced the mobs for creating chaos on a day he said should have been reserved for mourning the innocent victims killed by the Palestinian terror group Hamas on Oct. 7, 2023.

“It’s disgusting, disgraceful and appalling,” Holden told The Post of Monday’s sometimes out-of-control demonstrations.

Michelle Ahdoot, director of programming and strategy at End Jew Hatred, a grassroots group working to end antisemitism, said, “Immoral, pro-Hamas protesters thrown together by organizations which celebrate the Oct. 7 attacks, replete with the systemic targeting of Jews and the dissemination of hateful misinformation, are particularly deplorable.”

At one point around Union Square, a Jewish leader was surrounded, attacked and bloodied by a mob.

Todd Richman, co-founder Democratic Majority of Israel, was seen on social media holding an Israeli flag while a flood of protesters mocked him — and tried to wrest the flag away from him. 

Richman can be seen trying desperately trying to stand his ground as the keffiyeh-draped protesters taunt and accost him. 

“Get the f–k off the flag!” he is heard shouting. “Get off it!”

The mob then gangs up on him, with one striking Rochman and leaving him with a bloody nose.

Police finally move in and disperse the crowd, which is heard shouting, “Get out of here!” and someone calling him “a baby killer!”

It was unclear if anyone was arrested in the bloody scuffle, but at least a few people were cuffed by cops earlier elsewhere, including a woman who allegedly spit at someone.

Hundreds of demonstrators also gathered in front of the Low Memorial Library at Columbia University, chasing away pro-Israel protesters who had gathered earlier.

“Mobilize the antifada!” the largely peaceful crowd chanted. “Palestine will be free!” “Break the chains and watch them fall!” and “Israel go to hell!”

Earlier in the day, a pro-Israel crowd had greatly outnumbered the handful of counter-protesters.

Another anti-Israeli group gathered outside City Hall shortly before 3 p.m., with hundreds of demonstrators waving flags and calling for an end to the Israeli-Hamas war in the Gaza Strip — as well as the resignation of scandal-plagued Big Apple Mayor Eric Adams.

“Eric Adams must resign!” the crowd chanted. 

“His policies have been pro-Israel as well as used to beat protesters,” Kiswani claimed, apparently allegedly NYPD brutality. 

“His policies include doing mass shootings in trains,” she said, a reference to a recent police friendly fire shooting that wounded bystanders.

The crowd also demanded that federal money be made available for the US victims of Hurricane Helene, not Israel in its fight against the terrorists.

“Who are we going to put first?” a protester asked. “The people of North Carolina, the people of Tennessee, the people of New York — or these war criminals?” 

The mob then shouted, “Biden, you’re a liar!”

A crowd of as many as 75 formed also outside the New York University campus in Lower Manhattan, with both pro- and anti-Israel protesters gathering at the scene.

“We want the open, we want the openness, and we want the dialog,” said one NYU freshman. “It’s what America’s for. It’s terrible that this is what we have to do, which is terrible that Jewish, specifically Jewish students have to face this and on a daily basis.

“I was contemplating whether or not to wear my yellow pin today,” the student said, referring to the symbol in support of the Jewish hostages still held by Palestinian Hamas terrorists. “It was an inner battle I had prepared in time. I decided to do it because … I should.”

Organizers finally told the rabble rousers to go home Monday evening at Madison Square Park to avoid facing arrests by cops.

As throngs of protesters left the area, many chanted, “NYPD, go to hell.”

While the protesters left Madison Square Park, some of them continued marching north — with their sights set on Times Square.

Once at the Crossroads of the World, demonstrators were met by a heavy police presence. Officers ordered the group to remain on the sidewalk, leading to some jawing back and forth.

One anti-Israel demonstrator hoisted a Palestinian flag as supporters of the Jewish state condemned him – with one protester waving the Israeli flag above him, according to social media footage.

So far, ten people have been taken into custody at various points in Manhattan, police said.

The unrest had started early — vandals shattered windows at the CUNY Advanced Science Research Center in Upper Manhattan, scrawling “Divest now” on the building around 1 a.m. before fleeing.

NYPD Chief of Patrol John Chell vowed at a Battery Park briefing later in the morning, “We will protect everything, whether it’s protesters, New York City people just going about their business and everyone in between.

“When it crosses over into crime, we will be as professional as we can,” Chell said. “We’ll do what we have to do, and we’ll keep the day flowing.”

Cops said they were particularly on alert for a commemorative event to honor the Oct. 7 victims in Central Park in the evening.

The Oct. 7, 2023, attack on Israel by Hamas and the subsequent Israeli counter-offensive in the Palestinian-controlled Gaza Strip ignited widespread antisemitic demonstrations throughout the US over the past year, with those in the five boroughs among the most prominent.

Monday’s resurgent unrest frustrated Jewish residents and pols, who said they sought to mourn the dead and missing from the horrific sneak attack one year earlier.

“We should be given space to mourn, commemorate those who were massacred,” said city Councilman Eric Dinowitz (D-Bronx).

US Rep. Pat Ryan (D-NY) took to X to reflect on the anniversary.

“We all lost a part of ourselves on October 7,” he wrote. “But as we take this time to mourn and reflect on that tragic day, I want to remember the members of our Hudson Valley community who paid the ultimate price.”

Additional reporting by Joe Marino, Aneeta Bhole, Larry Celona, Caroline McCarthy, Hannah Fierik, Vaughen Golden, Dorian Geiger and Elizabeth Karpen