On Thursday while speaking to Brexit Party leader Nigel Farage on LBC, a London-based national phone-in and talk radio station, Trump was critical of the withdrawal agreement that UK Prime Minister Boris Johnson recently reached with EU leaders, the BBC reported.
"We want to do trade with UK and they want to do trade with us... To be honest with you... this deal... under certain aspects of the (Brexit) deal... you can't do it, you can't trade.
"We can't make a trade deal with the UK because I think we can do many times the numbers that we're doing right now and certainly much bigger numbers than you are doing under the European Union."
Trump, who has previously expressed his backing for Brexit, however did not elaborate on what difficulties he thought may arise in striking a US-UK trade deal.
In response, a Downing Street spokesperson said that Johnson's Brexit deal with the EU "ensures that we take back control of our laws, trade, borders and money".
"Under this new deal, the whole of the UK will leave the EU customs union, which means we can strike our own free trade deals around the world from which every part of the UK will benefit," the spokesperson added.
Meanwhile, other comments made by Trump led opposition Labour Party to accuse him of trying to "interfere" in the election, reports the BBC.
Speaking to LBC, the President said Labour leader Jeremy Corbyn would be "so bad" as Prime Minister and that Johnson was "the exact right guy for the times".
The UK is going to the polls on December 12 following a further delay to the country's departure from the EU, to January 31, 2020.
Johnson hopes to win a majority of seats so that he can get his deal through Parliament - while Corbyn promises another referendum if he wins the keys to 10 Downing Street.
( With inputs from IANS )