His comments came after the US president launched an extraordinary attack prime minister Theresa May and the UK’s now former ambassador to the US, Sir Kim Darroch, in a string of posts on Twitter.
Mr Trump hit out at Sir Kim after emails leaked on Sunday revealed the ambassador had called the president’s administration “dysfunctional” and “inept”.
Speaking to reporters on Thursday, Mr Johnson said: “I think the president’s tweets could perhaps be more diplomatic, there’s no doubt about that, but then sometimes some of the things I say could be more diplomatic.
“The most important thing is that the UK and the US have a very, very good relationship. That’s what we need to ensure.”
He added that the “real culprit in this whole business” was the person who leaked the emails.
Sir Kim quit his post, saying his job had become “impossible” after Mr Trump’s tirade against him.
It is understood he made the decision to resign while watching Tuesday’s televised Tory leadership debate, during which Mr Johnson refused to rule out replacing him.
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