Kathy Griffin shared a pic of her and one of De Niro, writing: 'The F**k Trump Club'.
"Mr. De Niro's comments were unscripted and unexpected", CBS said in a statement.
Trump and Trudeau have been engaged in a war of words over trade since the weekend's Group of Seven economic summit.
Jazz and Motown music played as guests waited for De Niro, chef Nobu Matsuhisa and other Nobu executives to arrive.
"I mean, this type of language is accepted in Trump's America", Seawright claimed.
Trump took to Twitter to blast Trudeau, calling him "very dishonest and weak" shortly after leaving the summit early aboard Air Force One.
Robert De Niro, fresh off the Tony Awards stage where he attacked the US president, and celebrity chef Nobu Matsuhisa are in Toronto today to launch a major new development.
"This guy just is a jerk", De Niro said.
"Bruce, you can rock the house like nobody else", De Niro continued. De Niro also noted the difficulty of obtaining tickets for Springsteen's shows and proclaimed that the singer-songwriter's perspective is especially needed "in these perilous times".
American viewers watching the Tonys at home only heard silence - the broadcast on CBS bleeped De Niro's expletive-heavy intro - but they saw the audience's largely enthusiastic reaction, the Associated Press reported.