The alleged victim, who cannot be named for legal reasons, told a police officer the Hollywood star had kissed his neck twice before grabbing him, saying the words "be cool, be cool".
In the interview, played to the jury on Tuesday at Southwark Crown Court, the man detailed an incident at an address where Spacey was staying in the Cotswolds, which happened after he accidentally let the actor's dog out.
He said the incident "shook" him and it was "unwanted" and that he has since "stopped ever watching or purchasing anything he (Spacey) had ever been involved in".
After telling the officer he apologised to Spacey for the dog momentarily escaping, the complainant said: "At which point he came towards me in a huggy motion and said 'don't worry about it, it is cool, it is cool.'
"We did an awkward man hug as I call it - he hugged me, I did a sort of pat on the back type of thing.
"At that point he kissed my neck twice and grabbed my crotch. He said the words 'be cool, be cool' twice.
"I put my arm between us and pushed him against a wall.
"I said 'I am sorry man, I don't bat for that team'."
The witness said that after he rejected Spacey, the actor had an "immediate panicked look on his face" before he left the room.
The man said the actor's "eyes opened quite wide" before he "immediately pushed past me" and into another room without saying anything.
The complainant told the officer of his "shock" at the incident but proceeded to say he "shook it off" before leaving.
He told police it "all happened quite swiftly" and that he had become "a bit teary" when he left the address.
Spacey, 63, has been described by the prosecution as a "sexual bully" as he stands trial accused of sex offences against four men between 2001 and 2013.
The defendant pleaded not guilty in January to three counts of indecent assault, three counts of sexual assault and one count of causing a person to engage in sexual activity without consent.
The two-time Academy Award winner also previously denied four further charges of sexual assault and one count of causing a person to engage in penetrative sexual activity without consent.
The trial continues.
10°C