The remarks were made to GB News at Trump International Golf Links, with Eric saying his father had "so much respect for the Queen".
"My mum knew so many of them for years and had a great relationship with Diana," he said.
"We'll happily send them back from America, but I'm not sure if you guys want them anymore- we might not want them anymore."
Trump added Harry and Meghan must "feel like they're a little bit on an island of their own".
"You can always have bad actors in everything. You can have spoiled apples in every orchard," he said.
"The institution of the royal family is beautiful and something that's admired by a lot of Americans and I think that should be protected."
