Trump also questioned the motives of some of the women.
"I can tell you that some of the women that are complaining, I know how much he's helped them, and even recently. And when they write books that are fairly recently released, and they say wonderful things about him. And now, all of a sudden, they're saying these horrible things about him," Trump said in an interview with NBC's Meet the Press.
"It's very sad because he's a very good person. I've always found him to be just a very, very good person. And, by the way, a very, very talented person. Look what he's done. So I feel very badly."
Trump added that "a lot of people are thinking he's going to run my campaign," but he wouldn't say whether those people were correct.
Ailes is a larger-than-life figure in American television history and a force in Republican politics.
Carlson's lawyer, Nancy Erika Smith, says 25 women have come forward with allegations about similar experiences that stretch across five decades. Ailes has denied the allegations.
Trump also defended Ailes in an interview with Bloomberg Politics as he flew home from Cleveland. Trump noted that he is close to Rupert Murdoch, who started Fox News, and that he knows "Rupert has great respect for Roger and everything Roger's done".
"I think it's so sad," Trump said. "He's such a great guy. Roger is - I mean, what he's done on television, is in the history of television, he's gotta be placed in the top three, or four or five. And that includes the founding of the major networks. So, it's too bad. I'm sure it was friendly."