Mr Prescott appeared to hit out after being hit by an egg outside a Labour Party rally in North Wales.
A 29-year-old man has been arrested.
" I was attacked by an individual - in the melee that followed I clearly defended myself "
The trouble followed angry scenes in Birmingham where Prime Minister Tony Blair was confronted by a cancer patient's partner complaining about health spending.
John Prescott said in a statement on Wednesday night: "I got off my bus into an already hostile crowd.
"I walked through all the jostling and I was attacked by an individual.
"In the melee that followed I clearly defended myself.
"I believe that someone is now being questioned by the police, and it would be quite improper and quite wrong to add any further comment."
An egg was thrown at Mr Prescott as he arrived at the Little Theatre, in Rhyl, North Wales, to address a Labour Party rally.
One eyewitness, farm labourer Ron Ingram, said: "Somebody threw an egg and Prescott just turned around and thumped them.
" Somebody threw an egg and Prescott just turned around and thumped them "
Eyewitness Ron Ingram
"I saw it.
"We were just protesting.
"The egg hit him and he hit out.
"There was pushing and shoving going on something terrible. It got quite nasty."
Mr Prescott was trapped against a wall before party supporters intervened.
He was led to safety by police.
Protesters, with placards in support of farmers and hunting, had earlier gathered outside the theatre.
Brendan Murphy, Conservative candidate for the Vale of Clwyd, which includes the town of Rhyl, called on the Deputy Prime Minister to resign.
Speaking outside the Little Theatre, Mr Murphy said: "He's just got to resign and get it over with.
"What sort of role model is he for young people.
"We don't want that kind of role model in Rhyl."
Mr Murphy said the protesters had every right to air their views outside the rally.
"Throwing eggs is almost a time honoured tradition in this country.
"It might hurt and sting your face a bit but it doesn't harm you.
"If politicians can't put up with things like that they shouldn't be in the job."
Later shadow cabinet member Andrew Lansley told BBC News Online: "All of us can be in positions when we can be provoked. But it is important not to lose your cool."
Asked whether the brawl would change William Hague's campaigning style, Mr Lansley said the Tory leader would continue to meet people.
For the Liberal Democrats, Simon Hughes said: "The guy should not have thrown the egg and the deputy prime minister should not have reacted in the way that he did.
"None of us is perfect but both of them have now to be dealt with by the law in the usual way," he said.
Earlier, Mr Blair faced the wrath of a cancer patient's distraught partner at Queen Elizabeth Hospital in Birmingham.
Sharron Storer, 38, was outraged that no bed had been available on Monday in the hospital's bone marrow unit for her partner, who has non-Hodgkin's lymphoma, a form of lymphatic cancer.
"Would you like to tell me what you are going to do to give these people better facilities?," she asked the prime minister.
The prime minister said afterwards that more investment was being put into the health service but that change took time.
Education Secretary David Blunkett told Channel 4 News that there were hundreds of thousands of patients were happy with their treatment in the NHS.
" I cannot remember Labour having such a single bad day of election campaigning in my time reporting politics "
Andrew Marr, BBC political editor
"There is still an absolutely enormous challenge in turning round the lack of investment and neglect.
"I am very sorry about Sharron Storer's partner. I just wished she'd voted in 97 and I wish she would vote this time."
The BBC's political editor Andrew Marr said: "I cannot remember Labour having such a single bad day of election campaigning in my time reporting politics."
William Hague joined in the controversy during a speech in the Midlands.
He said: "As Tony Blair discovered in Birmingham today, careful choreography and planted questions cannot shield him from the anger of ordinary voters."