Authorities say the 41-year-old Williams was briefly taken into custody on suspicion of assault Wednesday night after the apparent victim said he was attacked aboard a tour bus that was parked outside a downtown hotel.
Williams was released after investigators questioned him and several witnesses. Calls to representatives for Williams were not immediately returned.
Police said the man was treated at a hospital for a cut to his head. His name has not been released.
The performer is known for his HBO special, “Katt Williams: Pimp Chronicles Pt. 1,” and movie roles, including “Friday After Next” and “Norbit.”
He is scheduled to perform in Oakland on Friday.