The Hollywood Reporter quoted Cameron as saying Beck is a "f---ing asshole" and stating those who deny global warming exists have "got their head so deeply up their ass I'm not sure they could hear me."
The entertainment industry trade newspaper said Cameron made the remarks at a Fox Home Video press day Tuesday in West Hollywood promoting the Earth Day release of "Avatar" on DVD.
The response reportedly was to a question about conservatives' criticism of the movie's environmental and political themes.
Cameron also emphasized he intentionally focused on these in hopes of encouraging people to act responsibly in their treatment of the planet.
Beck fired back at Cameron Wednesday on his Fox News program, referring to "Avatar" as the "Smurf-murdering movie."
"Oh my God, really. It's time to walk away from the CGI just for a minute, Jim. Just for a second. I don't think he's upset with me though. He's also upset with you because you're a global-warming denier," The Hollywood Reporter quoted Beck as saying to his audience.