Cameron said a brawl was prevented when the television cameras returned from an advert break on the night in 1998 when his film scooped 11 Academy Awards.
He conceded a lot of people would rather he had gone through with it in hindsight, now Weinstein has been accused of sexual harassment and assault by a string of women, but said the argument was over the producer's treatment of director Guillermo Del Toro.
"I remember almost getting in a fight with Harvey Weinstein and hitting him with my Oscar," he said in an interview with Vanity Fair, published on Sunday.
"It was happening on the main floor at the [theatre]... and the music had started to play to get back in our seats. The people around us were saying, 'Not here. Not here'. Like it was okay to fight in the parking lot, you know, but it was not okay there when the music was playing, and they were about to go live."
"Harvey came up glad-handing me, talking about how great they were for the artist, and I just read him chapter and verse about how great I thought he was for the artist based on my friend's experience, and that led to an altercation," Cameron, 63, added.
Mexican director Del Toro said at the BFI London Film Festival last month that working with Harvey and Bob Weinstein on the 1997 sci-fi film nearly ended his Hollywood ambitions.
"I have got to tell you, two horrible things happened in the late nineties, my father was kidnapped and I worked with the Weinsteins," he said.
Lawyers for Harvey Weinstein, 65, have said he denies ever acting criminally and said he never engaged in any non-consensual sexual conduct.
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