The actor slapped Rock on stage at the Academy Awards in March, after the comic made a joke about Smith's wife.
On Friday, Smith released a video reflecting on the slap - the first time he has been seen discussing it - in which he reiterated his apology.
"Chris, I apologise to you. My behaviour was unacceptable," he said.
"I'm here whenever you're ready to talk."
Smith has previously only issued written statements about the altercation. In the video, on his own YouTube channel, he answers questions that appear to be written by fans.