In response to a Trump statement about handling protesters at one of his rallies, De Niro said: "He wants to punch people in the face?"
President Trump called Mr Trudeau "dishonest" and "weak" following the summit on Saturday.
De Niro's passionate criticism of Trump dates back to October 2016 when, in a wildly popular video clip, he called Trump a "punk", "b****** a href="http://www.businessinsider.com/trump-banned-from-nobu-robert-de-niro-says-2018-5" *banned Trump from all of his Nobu restaurants, which has locations all over the world". Many in the audience stood and cheered, while TV censors quickly bleeped out the offending words.
With all of his many moves that many believe have divided America, and helped to encourage a risky social climate where guns are prized, President Trump was not a popular figure at the 2018 Tony Awards. Fuck Trump", as he raised his fists, "it's no longer down with Trump.
The actor has been a vocal critic of Trump, twice declaring "f-- Trump" during the Tony Awards on Sunday night and receiving a standing ovation.
"Canada's foreign affairs minister, Chrystia Freeland, responded to the attacks by saying the country "does not believe that ad hominem attacks are a particularly appropriate or useful way to conduct our relations with other countries".
"Bruce, you can rock the house like nobody else", De Niro said.
The Raging Bull star also urged Americans to vote, and praised Springsteen's fight for 'truth, transparency and integrity in government.
"It's taken us about 50 years to realize how important diversification is and every political leader in Canada since that time has talked about the need for diversification", he says.
Tell us how you really feel Robert De Niro. "Who's gonna argue with him?" he said.