Iran Press/America: The ambassador was branded "a very stupid guy" by US President Donald Trump, after emails emerged calling the Trump administration "clumsy and inept".
It comes after President Donald Trump said Monday that the White House would no longer deal with the British ambassador, CNN reported.
The UK Foreign Office confirmed Sir Kim's decision to step down on Wednesday.
Sir Kim said he wanted to put an end to speculation, adding the leak had made it "impossible" for him to do his job.
Washington-London special relationship has come under strain in recent days following the leak of embarrassing confidential Foreign Office memos that presented an unflattering picture of US President and his administration.
101/211/205
Read More
Washington-London special relationship under strain following embarrassing leaked memos