Trump, who has just left Singapore after a historic meeting with the North Korean leader, was retaliating after De Niro spent the past few days publicly denouncing Trump.
“I watched him last night and truly believe he may be ‘punch-drunk.’ I guess he doesn’t realize the economy is the best it’s ever been with employment being at an all time high, and many companies pouring back into our country. Wake up Punchy!”
De Niro a staunch Trump opponent, repeatedly dropped the f-word to an audience at the Tony Awards Sunday night while referencing Trump.
The CBS television audience heard dead silence instead before he raised his arms — twice — and earned a sustained standing ovation.
He also urged people to vote in the November elections.
Then on Monday, De Niro apologized to Canadians for Trump’s insults after Trump called Prime Minister Justin Trudeau “weak” and “dishonest.”
De Niro said Trump’s remarks were a “disgrace.”
This isn’t the first time De Niro has gone after Trump. In January of this year, the actor called Trump a “f**king idiot” in a profanity-laced rant.
WATCH: De Niro’s past criticism of Donald Trump
*with files from Chris Jancelewitz