The 85-year-old chairman and CEO of Berkshire Hathaway told CNBC's Squawk Box Monday that the Massachusetts Democrat is "angry" and "demonizing."
"I think that she would do better if she was less angry and demonizing," he said (via Business Insider). "I believe in 'hate the sin but love the sinner,'" he said. "And I'm not sure that I've fully convinced Elizabeth Warren that that's the way to go."
"I think the whole nature of governing -- particularly when you've got a divided government like we have now -- is that you end up with bills that each side doesn't like but they like it better than doing nothing," Buffett added. "It does not help when you demonize ... the people you're talking to."
Warren has galvanized the progressive wing of the Democratic Party for advocating for financial reform and taking a tough stance on Wall Street. Though she is considered a possible contender for the 2016 presidential election, she has said she has no plans to run.
Buffett is the third-wealthiest person in the world, according to to Forbes annual billionaires list, which was released Monday. He is also an outspoken supporter of another potential presidential frontrunner, Hillary Clinton.