President Trump fired back at Joe Biden in an early morning tweet on Thursday, saying the former vice president is "trying to act like a tough guy."

"Crazy Joe Biden is trying to act like a tough guy. Actually, he is weak, both mentally and physically, and yet he threatens me, for the second time, with physical assault," the president said.

"He doesn't know me, but he would go down fast and hard, crying all the way," he added.

"Don't threaten people Joe!"

Biden reportedly said Tuesday at an anti-sexual assault rally at the University of Miami that he would have "beat the hell out" of Trump in high school over comments the president has made about women.

"A guy who ended up becoming our national leader said, 'I can grab a woman anywhere and she likes it,'" Biden said, according to ABC News.

"They asked me if I'd like to debate this gentleman, and I said no. I said if we were in high school, I'd take him behind the gym and beat the hell out of him."

Biden also said he's a "pretty damn good athlete" and has been in a lot of locker rooms in his life.

"Any guy that talked that way was usually the fattest, ugliest S.O.B. in the room," he added.

Biden was referring to the "Access Hollywood" tape in which Trump is heard making lewd comments about women.

Then-candidate Trump said when the contents of the tape were made public that it was "locker room talk."

Multiple women during the 2016 presidential race accused Trump of sexual misconduct.

Trump repeatedly denied allegations made against him.

Trump and Biden also sparred in the weeks before the 2016 election.

"Did you see where Biden wants to take me to the back of the barn?" Trump, who was then the Republican presidential nominee, asked supporters at a rally in Tallahassee, Fla.

"I'd love that. I'd love that," Trump continued. "Mr. Tough Guy. He's Mr. Tough Guy. You know, he's Mr. Tough Guy, when he's standing behind a microphone by himself."

Biden had remarked about taking on Trump "behind the gym" during a rally for Democratic nominee Hillary Clinton, slamming Trump's "disgusting" comments on women that Biden said amounted to "textbook" sexual assault.

"The press always asks me: Don't I wish I were debating him? No, I wish we were in high school - I could take him behind the gym. That's what I wish," Biden said.

Recent polling has shown Biden leading Trump in a potential 2020 matchup.

Updated at 8:08 a.m.