A man was slashed in the face when an argument turned violent at a longtime City Island seafood joint, police said Friday.

The dust-up took place at Tony’s Pier Restaurant around 9:30 p.m. Tuesday after a verbal dispute between two men escalated into a physical fight, cops said.

The suspect, seen in the surveillance footage from inside the restaurant, slashed the 24-year-old victim’s face with an unknown object, sources said.

Video footage shows him shoving the victim out of his seat, causing him to fall onto the floor — then walking away as stunned bystanders look on.

The victim was taken to Jacobi Medical Center for the cut to the left side of his face. He is not cooperating with investigators, police added.

Authorities are still looking for his attacker.