Britain's Foreign Office did not challenge the authenticity of the leaked documents.
It called the leak "mischievous behaviour" and said the public expects diplomats to provide honest assessments of the politics in the countries where they are posted.
The memos also characterised Trump's policy on Iran as "incoherent, chaotic."
Trump has frustrated European allies by withdrawing the United States from a complex deal designed to prevent Tehran from obtaining nuclear weapons and has seemed in recent weeks to be on the verge of armed conflict with Iran.
Darroch said there are doubts about whether the White House "will ever look competent" and that the only way to communicate with the president is by being simple and blunt.
He said that while Trump had been "dazzled" by British pageantry on a state visit hosted by Queen Elizabeth II in June, the successful visit would not lead to a fundamental shift in Trump's priorities.
"This is still the land of America First," he wrote.
Darroch's views may lead to some awkwardness , especially since Trump said shortly after his election in 2016 that Brexiteer Nigel Farage would make an excellent British ambassador to the United States.
(Only the headline and picture of this report may have been reworked by the Business Standard staff; the rest of the content is auto-generated from a syndicated feed.)
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