President Trump did not understand that the USA can not negotiate a trade deal with Germany alone and must deal with the European Union as a bloc, a senior German official told The Times of London.
Trump, who has repeatedly criticised the European Union, had welcomed Britain's 2016 vote to leave the bloc and said he would work hard to get a quick bilateral trade deal done.
"Every time she replied, "You can't do a trade deal with Germany, only the EU", the politician said.
The White House said the two also discussed the conflicts in Syria and Yemen and the need for a peaceful settlement to the crisis in Ukraine. "On the eleventh refusal, Trump finally got the message", said an unnamed senior German official.
The revelation is set to embarrass Prime Minister Theresa May and Foreign Secretary Boris Johnson who promised that a trade deal with the USA will negate any loss of business from the European Union following Brexit.
Brexiters argued that Britain would be free to negotiate quick trade deals with major economies around the world once it had left the EU.
During a trip to America in January, Johnson declared Britain will be "first in line" to strike a deal with the US.
Last year, American exports to the bloc were worth $270 billion dollars compared to $55b worth of goods exported to the UK. Whereas the USA exported $55bn from Britain and imported $54bn.
"[Brexit campaigners] are voicing an opinion about what the United States is going to do, I figured you might want to hear from the president of the United States what I think the United States is going to do", Obama said on 22 April, 2016.
President of the BDI industry group, Dieter Kempf, has advised Washington against engaging in protectionist policies and said "those who have trouble understanding how trade surpluses and globalization effects are created are invited to come here and take a look".
Merkel did not mention the exchange, saying only that she was very encouraged following her United States visit and adding that the EU's first priority was to complete work on a deal with Japan.