A perv grabbed a woman’s buttocks in an Upper East Side subway station this week — and then attacked her when she tossed her drink in his face, cops said.

The 31-year-old victim was going up the stairs at the 96th Street/Lexington Avenue station around 5:30 a.m. Monday when a creep grabbed her behind, police said.

When she turned around, she saw him trying to unbuckle his pants — an act that prompted her to toss the beverage from her thermos in his face, authorities said.

It was unclear what type of drink was inside the thermos.

He retaliated by grabbing the woman by the hair, hitting her in the face, and throwing her to the ground, cops said.

The suspect, who remains at large Thursday, is captured in a surveillance image wearing a black hoodie and face mask inside the station.