Mark Field has been suspended as a Foreign Office minister after grabbing a female Greenpeace activist at a black-tie City dinner.
The MP has apologised for confronting Janet Barker and marching her away as protesters interrupted a speech by Chancellor Philip Hammond.
But he said he had been “genuinely worried” she may have been armed.
Ms Barker told the BBC Mr Field 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.
BBC home affairs correspondent Daniel Sandford said there were also “very serious questions to be asked” about security, as a “large number” of protesters had apparently managed to “walk through” to the event at London’s Mansion House.
Footage of the incident involving Mr Field has been widely shared on social media, with several Labour politicians calling for him to be sacked.
A Downing Street spokeswoman said Prime Minister Theresa May had “seen the footage” and “found it very concerning”.
She added that Mr Field had “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 Mansion House on Thursday night, as Mr Hammond was beginning his speech on the state of the economy.
One of them began reading an alternative speech.
As Ms Barker walked past his table, Mr Field stood up, stopped her and pushed her against a column.
The Conservative MP for the Cities of London and Westminster then put a hand on the back of her neck and led her out of the room.