The US president has been removed from Twitter, Facebook and Instagram after posting messages the technology giants said could encourage violence, following an insurrection by a mob of his supporters.

Asked if Mr Trump helped incite a riot at the US Capitol on January 6, Mr McCormack said the president's social media comments were unfortunate, as was his refusal to accept the outcome of the US election.

But Mr McCormack also likened the riot to Black Lives Matter protests last year and said it should not be up to Big Tech to decide whose voices were heard.

"I don't believe in that sort of censorship," he told ABC radio on Monday.

"There's been a lot of people who have said and done a lot of things on Twitter previously that haven't received that sort of condemnation or indeed censorship."

However, the acting prime minister acknowledged social media companies were within their rights to close accounts.

"That's a matter for Twitter, they've made that call, they've got a company, they've got a business to run, and they've made that decision," he said.

Australia's competition watchdog has called for clearer rules to determine what content is acceptable on social media.

Queensland MP George Christensen is among several federal government backbenchers using social media to peddle misinformation being spread by supporters of Mr Trump.

But Treasurer Josh Frydenberg, a senior member of the leadership team, refused to censure him.

"George Christensen will make decisions he is accountable for," Mr Frydenberg told the ABC.

"He is a member of the coalition, he is a good local member for his constituency."

Mr Frydenberg said the prime minister spoke for the whole country and the government in expressing disgust about what happened at Congress in Washington DC, describing it as an attack on the beacon of democracy.

Mr McCormack would not be drawn on whether Mr Trump should be removed from office before his term ends on January 20.

But he did apply a distinctly Australian lens to the "unfortunate events" at Capitol Hill and dying days of the Trump presidency.

"Many people don't remember how you rode the horse, they remember how you dismount the horse," Mr McCormack said.

"But as far as Donald Trump and his presidency is concerned, and the last few days of his administration, well that's entirely a matter for the United States of America."

Australian Associated Press