Photographs of the Duchess of Cambridge on holiday in Provence, which had reportedly been taken with a long-lens camera, were published in the French edition of Closer, Italian magazine Chi, and the Irish Daily Star, which later suspended its editor.
Trump has now suggested that Middleton was at fault for choosing to sunbathe topless.
"Kate Middleton is great--but she shouldn't be sunbathing in the nude--only herself to blame," he posted on his Twitter page.
Trump added: "Who wouldn't take Kate's picture and make lots of money if she does the nude sunbathing thing. Come on Kate!"
Trump also commented on the story on Fox and Friends, saying: "While we're all fans of Kate, can you imagine why she would ever be out in the nude?
"Why would she be standing in the nude in a swimming pool or wherever she was. She's Kate. It's terrible what they did, it's terrible to take pictures, but boy, how can you do a thing so stupid?"
Referring to the nude photos scandal surrounding Prince Harry, Trump went on: "The Harry thing you can almost say he was less... his security did a pretty bad job. But to be outside at a swimming pool without a top on and you're Kate... you know. Maybe they can stop it but it is a very, very foolish thing she did."
A French court today granted an injunction preventing further publication of the topless photos.
The famous faces who have criticised the publication of the pictures include Kelly Osbourne and the Duchess of York, Sarah Ferguson.
Photo gallery - Kate and William in the Far East:
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