(Adds comments from Buffett, Berkshire Vice Chairman Charlie Munger)
By Jonathan Stempel and Jennifer Ablan
May 6 (Reuters) - Warren Buffett said on Monday that a trade war between the United States and China would be "bad for the whole world."
Buffett spoke after U.S. President Donald Trump tweeted on Sunday that he will raise tariffs on $200 billion of Chinese imports to 25 percent from 10 percent beginning on Friday.
Trump also said he would soon slap a 25-percent tariff on $325 billion of Chinese goods that have not been taxed.
Major stock markets fell worldwide on Monday in response to the tweet, which preceded scheduled trade talks this week, and was a "rational" response, Buffett said on CNBC television.
Buffett's conglomerate Berkshire Hathaway Inc owns or invests in many companies that do business in China, including Apple Inc, in which it has a more than $50 billion stake, and Chinese electric car maker BYD Co.
"If we actually have a trade war it will be bad for the whole world," Buffett said.
A full-scale trade war is unlikely, he said, but "would be bad for everything Berkshire owns."
Berkshire Vice Chairman Charlie Munger, also speaking on CNBC, said Trump was not "totally crazy" for wanting higher tariffs on some goods, but that a trade war would be "massively stupid."
Despite the concerns, Buffett said it would be "nonsense" for investors to sell stocks based on negative headlines, adding that the United States and China will be the world's superpowers for the next 100 years and will always have tensions.
He also said the battle would not affect how Omaha, Nebraska-based Berkshire operates.
The company owns more than 90 companies including utilities, makers of industrial parts and chemicals, Geico auto insurance and Dairy Queen ice cream, and ended March with $191.8 billion of equity investments.
"We will buy the same stocks today that we were buying last week," and would be "delighted" if a good Chinese business expressed interest in a Berkshire transaction, Buffett said.
Trump on Monday tweeted that the United States has for many years lost $600 billion to $800 billion annually on trade, and "with China we lose 500 Billion Dollars. Sorry, we're not going to be doing that anymore!"
Buffett said tough talk ahead of trade negotiations was understandable, saying that for some people "the best technique is to act half-crazy," but it would be ineffective to "shake your fist first and then shake your finger later on."
He added that Trump's planned tariffs raise the stakes for Chinese leader Xi Jinping.
"You're talking about two personalities who are very much used to getting their way in politics, and talking about how they will be perceived in their own country in terms of their behavior," Buffett said. "It gets very complicated."
Buffett said the trade dispute has already had an effect on Berkshire's BNSF railroad.
Meanwhile, Jim Weber, the chief executive officer of Berkshire's Brooks Running unit, said in an interview last week that his company was ending most shoe production in China and moving it to Vietnam because of tariff concerns.
Buffett also said the United States should bolster its trade relations with Canada and Mexico.
"We've got lots and lots and lots of common interests," he said. "Trade with Mexico and Canada is enormously important. We should treat them as neighbors, and not adversaries."
Reporting by Jonathan Stempel and Jennifer Ablan in New York; Editing by Jeffrey Benkoe and Nick Zieminski