Smith has since apologised to the Academy and to Rock, saying the violence was out of order.
The Best Actor winner, 53, on Tuesday morning posted a lengthy note on Instagram saying he was ashamed of his behaviour at the awards show.
"My behaviour at last night's Academy Awards was unacceptable and inexcusable," Smith wrote. "Jokes at my expense are a part of the job but a joke about Jada's medical condition was too much for me to bear and I reacted emotionally.
"I would like to publicly apologise to you, Chris. I was out of line and I was wrong. I am embarrassed and my actions were not indicative of the man I want to be.
"There is no place for violence in a world of love and kindness."
His mother, Carolyn Smith, told Philadelphia news station Action News that her son's behaviour was out of character.
"He is a very even, people person. That's the first time I've ever seen him go off. First time in his lifetime.
"I've never seen him do that."
She added that she was "proud" of her son for being himself.
"I know how he works, how hard he works," she said.
"And he never half steps. I've been waiting and waiting and waiting. When I heard the name, I was just, 'Yes!'
"I thought he should have been given one [Oscar] for all of them [his films]."
Australian comedian Jim Jefferies slammed the 53-year-old King Richard star in a fiery radio appearance.
In an interview with Kyle and Jackie O this morning, US-based Aussie comic Jefferies firmly took Rock's side in the jaw-dropping rant.
"It's not on. You can't just hit someone in the face at work, and not be dragged out of the bloody room and still get to have an award straight afterwards," he said.
He also addressed Smith's Best Actor speech, in which the tearful star spoke of defending his family from "disrespect" and said sorry to the Academy for his earlier behaviour.
"The apology just sucked. He apologised to the Academy, he apologised to his fellow actors – they didn't get bloody hit in the face, apologise to Chris!"
