"I would like to publicly apologise to you, Chris," he said in a statement. "I was out of line and I was wrong."
It comes after the Oscars film academy condemned Smith over the incident and announced a formal review.
The star slapped Rock in the face on stage after the comic made a joke about the actor's wife, Jada Pinkett Smith.
Rock had taken aim at Pinkett Smith's shaved head, a result of the hair-loss condition alopecia.