Police say a man instigated a fight with an anti-gay slur, then slashed the victim at a West Village McDonald's Sept. 19. View Full Caption NYPD

MANHATTAN — Cops are on the hunt for a knife-wielding suspect who allegedly slashed a 22-year-old patron after hurling anti-gay slurs at the victim when his transgender girlfriend tried to use the women's bathroom at the West 3rd Street McDonald’s, police and sources said.

The problems began shortly after 7 p.m. at the crime-plagued West Village fast-food-joint when the alleged victim and his transgender girlfriend were accosted at the entrance to the women's bathroom by a male patron who allegedly hurled anti-gay slurs at them.

"You're going to the wrong bathroom," the suspect said, according to sources. The man then threatened to "f--- them up"

The pair walked outside the West 3rd Street and Sixth Avenue location to escape the attacker, who police described as 5-foot-10 and weighing between 300 and 350 pounds, only to have him follow them out and try to take a swing at one of them, sources said.

One of the victims returned the punch, then kneed the assailant in the groin, sending him down to the ground, sources said.

The suspect pulled out a razor blade and repeatedly slashed the victim in the elbow, face, back and neck, police said.

The suspect fled and is now wanted for assault as a hate crime, cops said.

The victim was taken to Bellevue Hospital and received multiple stitches, police said.

The episode was the latest attack for that McDonald’s location, which has been a hotbed of violence to Village residents and elected officials.

In April, the fast-food restaurant was outfitted with surveillance cameras for cops to monitor after a string of assaults.

One major brawl occurred on St. Patrick’s Day this year, when two groups of teens were caught on cellphone camera fighting outside the venue.

Damian Furtch was caught on surveillance being beaten by another patron who he said bombarded him with anti-gay slurs on the sidewalk outside of that McDonald's location in March 2011.

And two patrons — Denise Darbeau and Rachel Edwards — were indicted for burglary after allegedly hopping the counter in Oct. 2011 to attack a McDonald's worker Rayon McIntosh, who was cleared of beating them with a metal grill cleaner.

McDonald’s, meanwhile, had hired two private security officers after City Council Speaker Christine Quinn, who represents the neighborhood, called for a boycott until the burger joint beefed up security measures.

Carmen Paulino, the McDonald's franchise owner, said that "While the incident occurred outside of my restaurant, we are cooperating with the police in their investigation."

Police are requesting anyone with information about the latest attack can call 1-800-577-TIPS. Tips can also be submitted at NYPDCrimeStoppers.com or by text at 274637 (CRIMES) then entering TIP577.

Editor's Note: The intial version of this story incorrectly identified the victim as a transgender woman. The victim is a man, and his girlfriend is transgender.