In an interview with The Sun, the president said he was not aware of the comments made by the Duchess, and saying: “I didn’t know that. What can I say?
“I didn’t know that she was nasty.”
Trump also claimed he was “really loved” in the UK, despite massive protests when he visited last year and more of the same planned next week when he embarks on a state visit.
The US president begins his state visit to the UK on Monday and will meet members of the royal family, including the Queen, but new mother Meghan will not be present.
When asked about the duchess suggesting she would leave America for Canada if he was elected, Trump said: “A lot of people are moving here (to the US).”
Trump said LA-born Meghan will make “a very good” American princess, and said of her joining the royal family: “It is nice, and I am sure she will do excellently.
“She will be very good. I hope she does (succeed).”
As with last year’s visit, protesters are planning to take to the streets to make clear their opposition to the US leader and his policies.
Trump appears to be unfazed by the opposition against him, saying: “I don’t imagine any US president was ever closer to your great land.
“You know there was a time quite a while ago, six or seven years ago, when a group of people came out against me in some form.
“They were totally over-ridden by another group of people that was far larger and everybody said, ‘let’s take a pass’.
“Now I think I am really — I hope — I am really loved in the UK. I certainly love the UK.”
In the same interview, Trump also came out in support of Boris Johnson’s Tory leadership bid.
The president used an interview with the same paper last year to drop a bombshell on Theresa May, saying her Brexit plan would “kill” any future US trade deal.