During a Q&A session at the Tribeca Film Festival on Saturday, the two-time Oscar-winner was asked by his Silver Linings Playbook co-star Bradley Cooper if there was any role he would never take.
"You want to guess? I'll give you one guess and I'll tell you," De Niro said before pausing, Page Six reports. He then said, "Donald Trump."
Back in March, De Niro bluntly called Trump an "idiot" during a speech in Los Angeles.
"A college education is important, but education without humanity is ignorance. Look at our president. He made it through [the] University of Pennsylvania, so he was exposed to a quality education, but he's still an idiot," the actor said. "No, don't boo, baby. This is for real. We have to do something about it, sorry. He lacks any sense of humanity or compassion. Of course, he did have to overcome the curse of growing up rich and spoiled and endure the heartbreak of bone spurs, maybe that had an effect."
Although the event he spoke at was supposed to be apolitical, De Niro said, "To be silent in the face of such villainy is to be complicit, and it's especially appropriate tonight because Trump treats education as a con, a way to make a profit at the expense of the suckers."
De Niro also played former FBI Director Robert Mueller, the special counsel leading the independent investigation into Russia's role in the 2016 election, for a Saturday Night Live sketch with his Meet the Parents co-star Ben Stiller as Trump attorney Michael Cohen.
During his opening remarks at the Tribeca Film Festival last week, De Niro said he would love to be back on SNL to play Mueller again.
"I hope there's a couple where I interrogate [Trump] then I arrest him and then I escort him to jail," De Niro said.
"The country has had a bad year, and you — the press — have taken a lot of hits," De Niro later told reporters, CBS News reports. "America is being run by a madman who wouldn't recognize the truth if it came inside a bucket of his beloved Colonel Sanders Fried Chicken."
De Niro is now working on Martin Scorsese's The Irishman, and recently earned an Emmy nomination for playing convicted Ponzi schemer Bernie Madoff in HBO's The Wizard of Lies.