He also told the tabloid that he'd shared advice with May during Britain's negotiations with the European Union and she ignored it. Tens of thousands of people gathered in London for a series of demonstrations against his visit.
"He said you are losing your culture, and standing beside her today at Chequers he said the same thing, that he thinks immigration is damaging to the United Kingdom".
"The relationship between our two nations is indispensable to the cause of justice, liberty and peace", Trump said just before the pair took questions.
He added: "I would have done it much differently".
"If you look, she probably went the opposite way". And that is fine. Instead he cryptically said that she'd found his proposal "too brutal". "That Brexit is a very tough situation, it's a very tough deal".
"It was not the deal that was in the referendum".
"I predicted Brexit. I was cutting a ribbon for the opening of Turnberry - you know they totally did a whole renovation, it is attractive - the day before the Brexit vote", Trump said. "So a lot of people don't like it".
Their meeting lasted almost an hour and was the final engagement in Mr Trump's two-day working visit to the UK.
"He is out of control and an embarrassment".
He was due to fly to one of his golf courses in Scotland later on Friday where he will stay until Sunday when he flies to Helsinki for talks with Russia's Putin where he said he would bring up the issue of nuclear disarmament.
The Queen all smiles as she shakes hands with Donald Trump and wife Melania - even though it looked like the US President broke royal etiquette.
"Moral outrage is water off a duck's back to Trump", the group added.
However, Trump ruled out May pursuing "no deal" - a move favoured by hard Brexiteers - saying there was no way the Prime Minister could walk away from the Brussels talks without an agreement. (Until) I remember her desperate rush to invite him, her repeated reluctance to criticise his Muslim ban or caging of children, her chasing him for a bad trade deal. As you'd imagine, his appearance has attracted a fair bit of attention, prompting (among many things) a giant 20ft baby blimp to be floated above Parliament Square as part of a huge protest.
In this interview, Mr Trump said: "You have a mayor who has done a awful job in London".
"I think he has done a bad job on crime, if you look, all of the terrible things going on there, with all of the crime that is being brought in", he said.