Labour MP Paul Farrelly has admitted he "wrestled" a man to the floor inside the Houses of Parliament.
The MP for Newcastle-under-Lyme described the altercation as "a John Prescott moment" and said it was an act of self-defence.
The Daily Mail named the man as Bjorn Hurrell, and said he was left with a cut above his eye.
Scotland Yard said it had not received complaints about the incident.
The altercation happened on Thursday evening during a karaoke party at Parliament's Sports and Social club.
Mr Farrelly told the BBC he was waiting for some guests in the club, a staff bar in Parliament.
He said: "There was a man there behaving very rudely and badly and pushing people, and I had a word with him about his behaviour."
Mr Farrelly said the man took a swing at him and pushed him to the ground. When he got up the man "clearly wasn't going to stop", so Mr Farrelly said he acted in self-defence and pushed the man to the ground and restrained him.
"It's always regretful to respond to provocation, but actually I think any normal person who is capable of defending themselves would have done exactly as I did.
"It happened to John Prescott a few years ago. It seems to have happened to me now."
Mr Farrelly added he had not heard from the police, but he would be very happy to help them and explain he was acting "entirely in self-defence".
Friends of Mr Hurrell, who delivers newspaper in the Palace of Westminster, told the Mail he had been enjoying the karaoke night he helped his mother organise.
The friends claimed the altercation began at the bar, and Mr Farrelly then confronted Mr Hurrell in a corridor outside the bar.
Friends said Mr Hurrell kept repeating "remember you're an MP", but Mr Farrelly continued and ended up wrestling him to the ground.
A friend told the Mail: "Bjorn was really shaken up that he had been attacked, let alone in the Houses of Parliament by an MP."
The Mail carries a picture of Mr Hurrell, 46, with a cut and swelling over his left eye, and says he is due to make a formal complaint about Mr Farrelly's behaviour to Parliament.
Mr Farrelly is a strong critic of anti-social behaviour, saying on his website: "Decent people should not see their lives blighted by nuisance and anti-social behaviour, nor should our children be led astray by a mindless minority."
In 2001, Deputy Prime Minister John Prescott brought the election campaign to life when he hit a voter who threw an egg at him in Rhyl.