An NYPD officer is under investigation after allegedly assaulting a Coney Island man over a spilled drink. Raymond Crespo was hanging out at Mermaid Ave and W 32nd St on July 8 when one of his buddies knocked his cup, filled with alcohol, onto ground. His friend, Crespo said, saw patrol officers nearby and did not want an open container summons. Cup allegedly rolled and spilled toward Officer O’Keefe Thompson’s foot. “He comes at me and says, ‘Hey, boy, you gotta clean this s— up’ and yada yada yada. I was like, ‘No, I’m not cleaning nothing up,’ ” Crespo said. Thompson allegedly grabbed 22 years old Crespo, pushed him against a nearby deli gate and then to the ground. “He said, ‘I’m from Brownsville, and I will f–k your a-s up’ ” said Crespo, who tells he threatened to sue the officer and arrogantly invited him to cuff him. “At that point he rushed me, but I went into the store. He grabbed me, started swinging me.” He added he latched onto the store’s gate to try to stay inside, but to no avail. “As soon as I let go of the gate, I hit it on the right side of my eye. And boom, I let go of the door, I come outside, and he’s dragging me.” With an injury to his right eye, Crespo went to Coney Island Hospital, where he reported the incident to cops. He tells he suffered a concussion. Crespo was not arrested after the encounter, but the following day, Crespo was on his way home when a friend warned him to lay low because the same officer was looking for him. Crespo told he refused and then saw Thompson, in plainclothes, approach him. “He’s over my body saying, ‘You’re gonna s— on my name? You’re gonna really s— on my name? You know what I should do to you?” added Crespo. A few later, Crespo told he encountered Thompson again, while on duty, who tried to smooth things over and invite him out for drinks. Thompson was placed on modified duty, an NYPD spokesman confirmed Monday. The spokesman declined to comment on investigation.