- Trump's former chief of staff said it was "manifestly false" of the ex-president to suggest the Capitol rioters posed "zero threat."
- Trump claimed last week that the rioters on January 6 posed "zero threat."
- Five people including a police officer died as a result of the attack.
"I was surprised to hear the President say that," Mulvaney told CNN.
"Clearly there were people who were behaving themselves, and then there were people who absolutely were not, but to come out and say that everyone was fine and there was no risk, that's just manifestly false - people died, other people were severely injured."
"It's not right to say there was no risk. I don't know how you can say that when people were killed," he said.
Last week, Trump spoke to Fox News about the events of January 6 in comments that significantly represented the nature of the attack. Hundreds of his supporters had breached police lines to enter the Capitol building after the president repeatedly and falsely claimed the election had been "stolen" from him due to widespread voter fraud.
"It was zero threat right from the start - it was zero threat," Trump told Fox News on Thursday.
"Look, they went in. They shouldn't have done it. Some of them went in and they're hugging the police and the guards. They had great relationships. A lot of the people were waved in and then they walked in, and then they walked out."
Around 140 officers were injured during the attack, according to the head of the Capitol Police union.
Mulvaney, who served as Acting Chief of Staff between January 2019 and March 2020, was one of several senior Trump officials who resigned in the wake of the attack. During the siege, he had criticized President Trump for failing to issue a stronger statement condemning the violence and urging supporters to go home.
Despite his condemnation of Trump's behavior around the Capitol riot, Mulvaney told CNN he would "absolutely" support Trump if he sought the Republican presidential nomination in 2024.