President Donald Trump warned ex-Attorney General Eric Holder he had "better be careful what he's wishing for" Thursday in response to Holder's remarks that Democrats should "kick" Republicans when they "go low."

Holder, speaking with supporters of Georgia Democratic gubernatorial candidate Stacey Abrams last weekend, quoted and then rejected former First Lady Michelle Obama's magnanimous comment to supporters that "when they go low, we go high."

"No, no. When they go low, we kick them," Holder said. "That's what this new Democratic Party's about."

Fox News host Steve Doocy asked Trump what that said to him about the tenor of modern politics.

"He better be careful what he's wishing for," Trump said. "That I can tell you … That's a disgusting statement for him to make. For him to make a statement like that is a very dangerous statement."

Trump came under criticism for suggesting to supporters that they should "knock the crap out of" any protesters at his 2016 campaign rallies and saying he would pay their legal fees.

He said his rallies were "calm" and packed with peaceful people. He also addressed Holder's White House ambitions; the former Obama administration official has said he is considering making a run in 2020 against Trump.

"Holder, he's got some problems, and I don't see him running, and if he did run, I think he gets gobbled up before he ever gets to the election itself. I think the primaries would gobble him up," Trump said.

Holder's combative comments followed ones made to CNN by 2016 Democratic nominee Hillary Clinton, who said Republicans didn't deserve to be treated civilly.

"You cannot be civil with a political party that wants to destroy what you stand for, what you care about," Clinton said. "That's why I believe, if we are fortunate enough to win back the House and/or the Senate, that's when civility can start again. But until then, the only thing the Republicans seem to recognize and respect is strength."