Police are trying to determine whether there were anti-gay comments during the incident, which was caught on camera and may be disturbing to some.
It happened shortly after 11 p.m. Tuesday night at the Dallas BBQ restaurant on Eighth Avenue in Chelsea.
A man, 32, says he was punched and kicked by the suspect and suffered bruising to the face, while another man was hit with a chair, suffering injuries to the left side of his face.
Both victims, who are acquaintances, refused medical attention.
Police released surveillance video of the suspect entering the restaurant.
A witness recorded the scene.
"I grabbed my phone because I thought this was a silly little argument with two guys. I thought, this will be funny, let's record," the witness said. "Then all that happened, and I thought, keep recording because nothing like this should ever happen. I've never seen anything like this in all my years."
He was seated just a few feet away when the altercation quickly erupted into a series of kicks and punches being thrown at one of the victims.
"Stood up, dropped him and then proceeded to stomp on his head. Everyone's trying to get the guy off him," the witness said.
The fight was temporarily broken up only for the suspect to return with a chair just moments later, striking the other victim over the head.
"People were trying to break it up, but once that chair went, once that guy was hit with the chair, he was out. And the restaurant pretty much cleared after that," said the man who recorded the video. "He could have killed that guy. The guy could have been completely dead. I don't know if he was homophobic and in the wrong place."
There are no arrests and the investigation is ongoing.
In a written statement, New York City Councilman Corey Johnson said, "I am appalled and angered by the senseless act of anti-LGBT hate violence that was perpetrated last night at a restaurant in my district. The fact that this attack took place in the neighborhood of Chelsea, a place known around the world for its acceptance of all people, is particularly outrageous. There must be zero tolerance of hate crimes, the most insidious of crimes as they target entire communities of people. I urge the perpetrators of this act to turn themselves in immediately. My office is in communication with the New York Police Department and the NYC Anti Violence Project. I urge anyone with information about this case to contact Crime Stoppers at 646-610-6806".