Mr Abbott said he was headbutted by a same-sex marriage campaigner in a Hobart street on Thursday who told him: 'You deserve it because of all the things you've said.'

Mr Abbott told 2GB he was walking back to his hotel following a meeting with a newspaper editor when he was beckoned by a man in the street.

"A fellow sung out at me 'Hey, Tony', I turned around, there was a chap wearing a vote 'Yes' badge," he said.

"He says 'I want to shake your hand'. I went over to shake his hand and he headbutted me."

A boxer during his university days, Mr Abbott was critical of the man's head butt: "He wasn't very good at it, I've got to say. But he did make contact. The only damage was a very, very slightly swollen lip."

"He didn't have a blood nose or break his nose or anything like that," a spokesman for Mr Abbott had earlier told AAP, while refusing to elaborate on the incident or injuries.

Mr Abbott, who did not say whether he had reported the incident to police, was with a member of his staff who "briefly grappled" with the alleged assailant: "He then ran off, swearing his head off basically".

Mr Abbott said the incident was a reminder of how ugly the same sex marriage debate was getting.

"The ugliness is not coming from the defenders of marriage as it's always been understood," he said.

"The ugliness, the intolerance and indeed in this instance, the hint of violence is coming from those who tell us, in the name of decency and fair-mindedness and freedom, we've got to allow same-sex marriage."

Opposition leader Bill Shorten condemned the violence on social media.

The Independent MP for Sydney, Alex Greenwich, released a statement on behalf of The Equality Campaign condemning the violence reported by Mr Abbott.

"We condemn the violence against Tony Abbott that has been reported tonight," the statement read.

"There is never a place for violence or abuse.

"Marriage Equality is about respect and dignity for every Australian. There is no room for any disrespect either physical or verbal in this national debate.

"Our campaign has always and will continue to call for respect and everyone involved in this debate to act in a respectful and dignified way."

Reaction on social media to the incident ranged from disbelief to shock and anger.

Mr Abbott said it was the first time he had been physically attacked in at least 10 years since he was "thumped" while visiting a psychiatric hospital in Victoria.

"One of the patients punched me, as I was later told, because he was under the impression that I was his dad," he said.

Mr Abbott added: "It was just very disconcerting to find the love is love brigade, or a least someone who was advocating a yes vote, should under the guise of wanting to shake your hand, in fact try to give you a so-called Liverpool kiss."

Asked how he knew the assailant had attacked Mr Abbott because of his stance on same-sex marriage, Mr Abbott said: "As he was scarpering away, amidst all the eff'in' this and eff'in' that, was a 'You deserve it because of all the things you've said'."

Mr Abbott laughed as he said it was clear the incident was "politically motivated violence".

However, he said he would be disappointed if the incident led to round-the-clock protection for prominent politicians.

"Look, 99.9 per cent of the exchanges that I've had over the years have been courteous even from people who don't agree with me," he said.

"But this was, I have to say, just a little bit disconcerting because it was so out of the blue."

Asked why he did not fight back, Mr Abbott said: "Perhaps I lack the pugilistic skills of an Andrew Bolt" - a reference to an incident in Melbourne in June when Mr Bolt fought back against two assailants.

"It all happened in a matter of just a few seconds and the thought certainly went through my mind, but then I thought that just escalates."

A strident campaigner against same-sex marriage, Mr Abbott told Sky News on Tuesday that the the government's postal plebiscite was a "fundamental mistake".

"Putting this matter to a plebiscite without giving the public the detail upon which they're having to vote. So they're asking us to sign a blank cheque."

Mr Abbott used the incident to reiterate his claim that supporters of same-sex marriage were overwhelmingly guilty of bullying and intimidation.

Mr Abbott said bullying would intensify if same-sex marriage is legalised in Australia.

"What I underestimated in the streets of Hobart today is just how angry and intolerant some of the same-sex marriage people are," he said.