Rudy Giuliani says Trump has been completely cleared by the Michael Cohen affair and there is no reason he should be impeached.

Giuliani, Trump's personal counsel, was speaking on Thursday during a golf trip to Scotland.

Cohen pleaded guilty on Tuesday to eight charges, including campaign finance violations that he said he carried out in co-ordination with Trump.

Giuliani said Trump "didn't collude with the Russians, he didn't obstruct justice, everything Cohen says has been disproved."

"You could only impeach him for political reasons and the American people would revolt against that," he told a Sky News journalist from what appeared to be Trump International Golf Links in Aberdeenshire.

Wearing a Trump Scotland cap and speaking from his golf buggy, Giuliani said tape recordings say "very clearly that Cohen did it on his own, didn't tell the president until much later."

"It demonstrates that Cohen's a liar and the US attorney in the southern district of New York extraordinarily called him a liar."

He added that the president had been vindicated by the Cohen incident.

Trump told US media on Thursday he believed the country's economy would crash if he was impeached.

"If I ever got impeached, I think the market would crash. I think everybody would be very poor," he said in an interview with Fox & Friends.

Australian Associated Press