Mark Field has been suspended as a Foreign Office minister after grabbing a female Greenpeace activist at a black-tie City dinner.
Mr Field has said he regrets confronting Janet Barker and marching her away as protesters interrupted a speech by the chancellor.
But he said he had been "genuinely worried" she may have been armed.
Ms Barker told the BBC he should "reflect on what he did" and suggested he "go to anger management classes".
"He certainly manhandled me in a way in which was very disagreeable," she said, but added that she did not intend to complain to the police.
Footage of the incident has been widely shared on social media, with several Labour politicians calling for Mr Field to be sacked.
A Downing Street spokeswoman said Prime Minister Theresa May had "seen the footage" and "found it very concerning".
She added: "The police have said they are looking into reports over this matter and Mark Field has also referred himself to both the Cabinet Office and the Conservative Party. He will be suspended as a minister while investigations take place."
Climate change protesters - wearing suits, red dresses and sashes with "climate emergency" written on them - entered London's Mansion House on Thursday night, as Chancellor Philip Hammond was beginning his speech on the state of the economy.
One of them began reading an alternative speech.
Mr Field stood up, stopped Ms Barker and pushed her against a column as she walked past his table.
The Conservative MP for the Cities of London and Westminster then led her out of the room.
'We were polite'
Ms Barker told the BBC the purpose of the protest had been to speak to "men who are in power, the bankers, the investors that are continuing to invest into fossil fuels".
"We were polite with people and said: 'We're here to deliver a message'," she said.
Before his suspension, Mr Field told ITV News that guests had "understandably felt threatened" and he had "instinctively reacted" when Ms Barker rushed past.
"There was no security present and I was, for a split second, genuinely worried she might have been armed," Mr Field said.
He added: "I deeply regret this episode and unreservedly apologise to the lady concerned for grabbing her, but in the current climate I felt the need to act decisively to close down the threat to the safety of those present."
Asked if she felt Mr Field's actions amounted to criminal assault, Ms Barker said: "No, I don't think so. I don't want this to turn into a mud-slinging match."
The activist, who travelled from her home in Wales to take part in Thursday's protest, said: "350 people were there and only one person reacted that way.
"It's more the behaviour of that individual. I want him to reflect on what he did and not do it again. Maybe he should go to anger management classes."
Labour's shadow women and equalities minister Dawn Butler tweeted: "This is horrific... [Mark Field] must immediately be suspended or sacked."
'Over-reaction'
But Mr Field was defended by some of his colleagues, with Conservative MP Johnny Mercer tweeting: "He panicked, he's not trained in restraint and arrest, and if you think this is 'serious violence' you may need to recalibrate your sensitivities. Calm down, move on, and be thankful this wasn't worse."
Conservative leadership contender Jeremy Hunt, who, as Foreign Secretary, is Mr Field's boss, said: "Mark has issued a full and unreserved apology. He recognised that what happened was an over-reaction.
"In his interest and in the interest of the lady involved we need a proper independent inquiry and that's what going to happen."
The City of London Corporation has said it is investigating how security was breached at Mansion House, adding it would be "reviewing arrangements for future events".