The chairman and CEO of Berkshire Hathaway has remained quiet about the Republican billionaire despite criticism from corporate leaders over Mr Trump’s response to deadly violence at a white nationalist rally in Charlottesville, Virginia.
CEOs have distanced themselves from Donald Trump since the riots by leaving White House business advisory councils, that were later disbanded.
Speaking to CNBC, Mr Buffett said: “I’m not in the business of attacking any president, nor do I think I should be.
“This country will move forward. It is important that government functions well. It’s important that both from the Government side and from the private side, that they try to maximise the degree to which this country moves forward.”
The 87-year-old business magnate, who was a supporter of Hillary Clinton in the 2016 presidential race, said he was disappointed with the result and that he would take a position in the 2018 campaign.
He said: “I worked for Hillary. I raised money for Hillary. I voted for Hillary. I was disappointed when she lost.
“But we have a President and we have North Korea.
“I won’t say if my candidate doesn’t win, and probably half the time they haven’t, I’m going to take my ball and go home.”
Mr Buffett added he had lived through 15 of the 45 US Presidents.
He said he bought stocks under 14 of those 15 starting with President Franklin D Roosevelt, who was elected in 1933.
He said: “The first one was Hoover. I was only 2 when he left so I hadn’t gotten active at that point.
“But Roosevelt was next. And I bought stocks under him, even though my dad thought it was the end of the world when he got elected.”