"We love your country", Trump said in comments carried by The Hill. It's very, very tough.
Mr Davis also said existing worldwide agreements - which include trade deals with other countries and agreements on aviation and nuclear power - should continue to apply during the period.
Trump provided British TV host Piers Morgan, a former "Celebrity Apprentice" victor, with an exclusive interview while visiting Davos, Switzerland for the World Economic Forum.
"I said [that] because of trade, but mostly immigration, Brexit is going to be a big upset".
Trump delivered the warning during a wide-ranging interview on the sidelines of the World Economic Forum in Davos, where he took his "America First" agenda to the global business elite.
A year ago it vowed to impose almost 300% punitive tariffs on airplanes manufactured by Canada's Bombardier.
Britain is impatient to launch talks on future ties with the EU and in particular on trade, but more guidelines will have to be adopted at a summit of European leaders in March for that to happen, based on progress made by then. I could name many countries and places that do.
May was similarly glowing in her praise of what she called a "really special relationship between the U.K. and the United States". And I support you militarily very much.
Britain's prime minister Theresa May, who met senior ministers to discuss their goals for the transition period on Monday, said via her official spokesman that while there was "broad agreement" on both sides, there were differences on "specific detail".
The transition period - also referred to as an implementation period - is seen as a way to minimise disruption when the United Kingdom leaves the European Union for things like business, holidaymakers and security.
Fox Cities homeless count finds 12 people sleeping outdoors
The youth survey results will help establish the need, and show the willingness to address that need, Querry said. Homeless Count 2018's Jennifer Westerman says volunteers in their group encourage the homeless to move indoors.
"I would have said the European Union is not cracked up to what it's supposed to be".
"I would have taken a tougher stand in getting out", he adds.
Previous year an economist said South Korea would like to secure a "quick deal" with Britain after Brexit. "And if we don't have it settled this thing could go to the wire". I like, as you know, I like Emmanuel.
Trump confirmed he will visit Britain later this year, where he believes he is "very popular".
Some Britons are angry at the prospect of a visit by Trump, with large protests expected when he does arrive. "I would have had a different attitude", he says in an ITV interview.
But several MPs asked by Reuters say her removal is a risky strategy for the party, which is divided down the middle over Brexit. While the interview has not yet aired, Britain's Mail on Sunday reported that Trump criticized May's approach to the talks ahead of Britain's departure from the bloc in 2019.
"I mean, I think that would be, maybe, going too far".
"I'm for women, I'm for men, I'm for everyone".
"If somebody said, go back into the Paris accord, it would have to be a completely different deal because we had a terrible deal", Trump said.
Sources said Williamson, the Defence Secretary, was the victim of smears following anonymous and incorrect briefings that he leaked intelligence, but an unnamed Foreign Office official criticised the tone of an interview he gave warning Russian Federation could kill many thousands of Britons.