The pair were among the A-listers who joined thousands of demonstrators gathered in front of the President-elect’s Trump International Hotel and Tower in the heart of his home town.
Mr De Niro thanked his “overrated” friends for coming in, a sarcastic reference to Mr Trump’s comments about Meryl Streep after she criticised him during a recent awards ceremony.
The film star proceeded to read out some messages Mr Trump could potentially live-tweet from his swearing-in ceremony tonight.
He suggested one tweet might be: "De Niro’s career is a disaster…he should give back his Oscars. Voting was rigged. There’s only one true raging bull and that is Vladimir Putin.”
And he called the billionaire businessman “a bad example of the country, of this city.”
The actor told the crowd: “The President-elect said our country was a dumping ground for the world. Really? These huddles masses yearning to breathe free built our country and the lifeblood of our strong, diverse beautiful New York City.
“They gave us the strength to prosper in the mid-seventies when the Government told us to drop dead. They gave us the strength to recover from the tragedy of 9/11.”
Alec Baldwin, Cher, Julianne Moore, Marisa Tomei, Sally Field and Nathalie Merchant also attended the We Stand United rally, organised by Greenpeace and MoveOn.
Other big names who appeared included New York Mayor Bill de Blasio and actors Rosie Perez, Mark Ruffalo and Alec Baldwin – who delighted the crowd with his impression of Mr Trump.
On a more sombre note, film-maker Mr Moore warned the crowd: “We’re at a very dangerous moment in history. As bad as you think it’s going to be, it’s going to be worse.”
“With a lot of work on our part, we will stop this man,” the film-maker said. “He will not last four years.”
Mr Moore called for “100 days of protest” against “sociopath” Mr Trump as he starts his presidency.
Mayor Bill de Blasio, a Democrat, called on Americans across the country to "rise up" and make their objections to the incoming administration heard.
He said: “Donald Trump always liked to say he built a movement, well now it's time for us to build our movement and that starts tonight, and it's all over the country, tonight, tomorrow and in the days to come.”
He urged the crowd to fight to preserve Obamacare, measures taken to protect the environment and LGBT rights gained under the outgoing President.
"Look at the thousands here tonight and that is only the beginning," he added.
A poll released by Quinnipiac University said 46 per cent of New York voters want to Mayor to try to get along with the President-elect - but 45 per cent believe he should be a national leader against Trump's policies.
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