He explained that spontaneity was not in the national security interest.
Mr. Trump is renowned for his broad pronouncements on issues of national importance on his Twitter feed.
Mr. Brennan also claimed that Mr. Trump didn’t fully appreciate the capabilities and intentions of Russia and also lacked to understand why President Obama has imposed sanctions on Russia for meddling in the election.
“I think Mr. Trump has to understand that absolving Russia of various actions that it’s taken in the past number of years is a road that he, I think, needs to be very, very careful about moving down.”
The remarks from Mr. Brennan, in an interview with Fox News Sunday, came a week after the release of a report by the Intelligence which claimed Russian President Vladimir Putin probably attempted to influence the presidential election.
Mr. Trump hit back at the CIA director in a series of tweets questioning whether he was the one who leaked the dossier full of unverified allegations
It is now developed that Mr. Trump underplayed the conclusions of the Intelligence community for months that Moscow hacked Mr. Trump’s rival, Democratic candidate Hillary Clinton’s campaign. He accepted the findings at a news conference on Wednesday.
Meanwhile, a report in the Sunday Times which claimed that Mr. Trump and Mr. Putin were arranging a summit in the capital of Iceland, Reykjavik has been denied by both Kremlin and Mr. Trump’s team.
Reykjavik hosted a major summit of 1986 – close to the end of the Cold War – between President Ronald Reagan and Mikhail Gorbachev, the leader of the then Soviet Union.
Mr. Brennan said that “talking and tweeting” would no longer be an option for Mr. Trump after he takes office next Friday. Mr. Brennan explained that spontaneity is not in the interest of national security and whenever a leader responds or reacts, he should understand that whatever he’s saying is going to have a profound impact on the country.
“It’s more than just about Mr. Trump. It’s about the United States of America.”
The CIA Director also criticized Trump for his tweet last Wednesday in which he accused the intelligence community of leaking an unverified dossier which claims that Russia has compromising information on Trump, which could be used for blackmail.
“What I do find outrageous is equating the intelligence community with Nazi Germany. There is no basis for Mr. Trump to point fingers at the intelligence community for leaking information that was already available publicly.”
Mr. Trump had responded with tweets quoting the Washington Post journalist Bob Woodward that the dossier should have never been presented at an intelligence briefing and the intelligence community should apologize for their mistakes. Mr. Trump added that the media should also apologize.
The claims have been described as “fake news” by President-elect Trump. Russia has also denied having any compromising information on Mr. Trump.