"We condemn it - the president and this administration - in the strongest possible terms," Kayleigh McEnany told reporters on Thursday amid growing calls for Trump's removal from office after his supporters on Wednesday stormed the US Capitol in unrest that resulted in four deaths.

"It is unacceptable, and those that broke the law should be prosecuted to the fullest extent of the law," McEnany said in the White House briefing room. She declined to take questions.

Trump, temporarily blocked from using Twitter and banned from Facebook for at least two weeks, made no public appearances on Thursday.

The Republican president pledged in an early morning statement to carry out an "orderly transition" of power to President-elect Joe Biden, but continued to claim falsely the election victory was stolen from him.

McEnany urged Americans to unite and reject the violence seen at the Capitol, and she said those working at the White House were committed to an orderly transition of power.

She blamed the violence on a small number of protesters who hijacked what she described as a largely peaceful gathering.

"What we saw yesterday was a group of violent rioters undermining the legitimate First Amendment rights of the many thousands who came to peacefully have their voices heard in the nation's capital."

Critics accuse Trump of fomenting the violence after he spent weeks whipping up his supporters with false allegations of fraud in the November 3 election and then urged supporters on Wednesday to march to the Capitol building.

Even after protesters stormed the Capitol, Trump praised them as "special people" and said he understood their pain.

McEnany sought to differentiate between peaceful protesters and those involved in the rampage.

"The violence we saw yesterday at our nation's Capitol was appalling, reprehensible and antithetical to the American way," she said. "Those who violently besieged our Capitol are the opposite of everything this administration stands for."

Australian Associated Press