President Donald Trump has lashed out on Twitter, telling Tonight Show host Jimmy Fallon to "be a man" and stop "whimpering" about the pair's infamous 2016 interview.

Last week, Fallon told The Hollywood Reporter about the personal anguish he felt over the backlash he received after messing up Trump's hair during his 2016 campaign appearance on Fallon's late-night talk show.

Commenting that it was "definitely a down time", Fallon said he'd received the public's message of disappointment loud and clear - and that if he could do things differently, he would.