Sen. Marco Rubio during an interview with CNN's Jake Tapper. CNN Sen. Marco Rubio said he apologized to Donald Trump for crude remarks Rubio made during a March campaign rally.

"You know what they say about men with small hands," Rubio said of Trump's hands during a campaign stop in March, before a lengthy pause. "You can't trust them."

In an interview with CNN's Jake Tapper that aired Sunday, Rubio said he apologized to Trump during one of the Republican presidential debates for the comment.

"I apologized to him for it," Rubio said. "I said, 'I'm sorry that I said that. That's not who I am, and I shouldn't have done it.'"

During Sunday's interview, the senator acknowledged his attack on Trump "embarrassed" his family, but came from a desperate place after he realized that his existing criticisms of Trump weren't working.

"I mean, this guy is out there every day mocking people, saying horrible things about people, but if you respond to him and somehow, you're hitting him below the belt?" Rubio said. "That was my sense at the time."

"What I didn't realize at the time was it's not who I am. And if you're not being who you are, it doesn't come across well," he added.

Rubio's comments about Trump's hands yielded one of the most noteworthy moments of the campaign.

During a Republican debate in March, Trump asserted that Rubio was mistaken about the size of his hands — and the implication that resulted from it.

"Look at those hands, are they small hands?" Trump said during the debate. "And, he referred to my hands — 'if they're small, something else must be small.' I guarantee you there's no problem. I guarantee."

Watch a clip of Rubio's Sunday interview below: