"Someone said it was joking about her [Jada's] disability. Well I'm going a bit thin, so I'm disabled. That means I can park right up next to Tescos now," he said.
"And I'm fat, that's a disease. I'm fat and balding, I should get f***ing benefits."
Pinkett Smith shaved her head last year after struggling from worsening hair loss.
In a 40-second video posted to Instagram in December, Pinkett Smith told fans, "Now at this point, I can only laugh… y'all know I've been struggling with alopecia.
"Just all of a sudden, one day…" she added, pointing to a hairless line on her scalp.
Despite public backlash over Rock's insensitive joke, Gervais insisted the comment "wasn't bad", while condemning Smith for slapping the Oscars host.
"You don't hit people over a joke, however bad it is. And it wasn't bad!
"That was like the tamest joke I would ever have told."
It's not the first time he's voiced his opinions on the slap, previously saying that he would never joke about Pinkett Smith's hair loss - rather, he would have made jokes about her "boyfriend".
The comedian's fans were keen to know what he would have said, having made jokes about his fellow celebrities while hosting the 2020 Golden Globes.
While testing new comic material at a show in London this week, Gervais said, "I'll get it out of the way. I have not got any Will Smith material. I trended when that happened and I was not even there."