Sen. Kamala Harris, D-Calif. and a 2020 Democratic presidential contender, apologized Saturday for laughing and saying "well said" in response to a man who described President Donald Trump's actions as "mentally retarded."

"When my staff played the video from my town hall yesterday, it was upsetting," she tweeted. "I didn’t hear the words the man used in that moment, but if I had I would’ve stopped and corrected him. I’m sorry. That word and others like it aren’t acceptable. Ever."

The senator told NBC News that, "I would never condone that kind of language being spoken by anybody about anybody. It is offensive. I have worked my entire career to do a number of things including to ensure our disability community receives the dignity and the rights that they deserve."

Footage of her response drew rebuke online. The exchange took place at a Friday town hall in New Hampshire, where a man who identified himself as being from Chennai, India, said, "Somehow a racist bigot gets into the White House and then he says if you're not my color you need to go back to your own country."

"So I am scared for this country," the man continued. "I am scared for the people of color in this country."

He then asked what Harris would do "to diminish" Trump's "mentally retarded" actions.

The crowd applauded the answer while Harris laughed and said, "Well said, well said."

"I plan to win this election, I'll tell you that," Harris responded. "It's going to be about working as hard as I possibly can to get there, because over the course of this next year that's what it's going to take to unseat him. Thank you for having the courage to stand up and say it is that there are a lot of people living with extreme fear right now in our country, extreme fear."

Speaking with CBS News, Harris denied hearing the phrase.

"I heard him talk about the other stuff," she said. "And then that came later. And it was not something that I really heard or processed, you know, in any way."

She called the remark "incredibly offensive," adding that you'd assume in 2019 that "people would have a much better understanding of how hurtful a term like that can be."