However, spokeswoman for May's office has disputed Trump's interpretation saying that agreement struck with the EU allows the UK to sign trade deals with countries throughout the world, including with the United States.
"We have already been laying the groundwork for an ambitious agreement with the US through our joint working groups, which have met five times so far," news agency Reuters quoted the spokeswoman as saying.
Under the deal secured with EU leaders on Sunday, the UK will leave the bloc in March with continued close trade ties. But the odds look stacked against May getting it approved by a divided British parliament.
The British leader on Sunday closed 17 months of painful talks with Brussels by sealing Brexit arrangements with the 27 other EU heads of state and government.
However, May faces a difficult task getting parliamentary approval for the deal.
(With inputs from news agencies)
Under the deal secured with EU leaders on Sunday, the UK will leave the bloc in March with continued close trade ties.