Dating from 2017 to the present day, Darroch in the leak emails said: "We don't really believe this administration is going to become substantially more normal; less dysfunctional; less unpredictable; less faction-riven; less diplomatically clumsy and inept."
The mails were leaked to the Mail newspaper on Sunday.
While speaking to reporters in New Jersey on Sunday night, Trump said that he hadn't seen the mails, adding that "the Ambassador has not served the UK well, I can tell you that".
"We're not big fans of that man and he has not served the UK well, so I can understand it," Trump said. "And I can say things about him but I won't bother."
Also on Sunday night, British Trade secretary Liam Fox told the BBC the leak was "unprofessional, unethical and unpatriotic".
He said that whoever released the emails had "maliciously" undermined the defence and security relationship with the US, "the most important global relationship that we have".
Foreign Secretary Jeremy Hunt, who is seeking to become the next Conservative leader and the UK's new Prime Minister, said the memos reflected a "personal view", not that of the UK government.
Hunt added it was the ambassador's job to give "frank opinions" but they did not reflect the government's view.
Meanwhile, the British Foreign Office has launched a probe to find the source of the leak.
( With inputs from IANS )