Meanwhile, an "entirely unscathed" Mr Abbott has used the incident to decry the "brave new world of same-sex marriage" and cement his claim the "yes" side was responsible for the increasing ugliness of the debate.

However, details were still unclear on Friday morning. Sky News reported that Mr Abbott's alleged assailant "at no stage" mentioned same-sex marriage during the altercation, but was wearing a "yes" badge. Mr Abbott told reporters his assailant had told him, "you deserve it because of what you've said".

Tasmanian police described the incident as an "alleged assault" and said they launched an investigation after contacting Mr Abbott, having first learnt of the matter through the media.

The former prime minister said his office reported the matter to the Australian Federal Police, and knocked back suggestions he needed bodyguards, arguing it was a good thing for Australians politicians to mix freely with the people.

The increasing ugliness of the campaign - which has involved brutal assaults on "yes" supporters including Kevin Rudd's godson Sean Foster - led Mr Turnbull to urge "calm and restraint" for the remainder of the postal survey process.

"We should have zero tolerance for disrespectful conduct and absolutely zero tolerance for violence of this kind," he told 3AW radio.

"Everyone should exercise calm and restraint, and people should recognise that they are not helping their case by engaging in violent language, abusive language, let alone physically violent conduct as Tony suffered from last night."

Mr Turnbull agreed with host Neil Mitchell the incident did not represent the "yes" case. "Overwhelmingly, Australians are engaging in this debate respectfully and harmoniously," he said.

Other Turnbull government ministers, including Foreign Minister Julie Bishop and Defence Industry Minister Christopher Pyne, also condemned the alleged attack on Mr Abbott and said violence had no place in the debate.

Finance Minister Mathias Cormann noted the alleged perpetrator "has done great damage to his cause".

Prominent "yes" campaigners were quick to condemn the attack and distance themselves from it, with Sydney MP Alex Greenwich telling Sky News: "This stupid clown in Hobart has nothing to do with our campaign."

On Friday morning, Mr Abbott spoke to reporters in Hobart and recounted details of the incident, including that the perpetrator "was of course wearing a 'yes' badge".

But it was not evident that the man raised the issue of same-sex marriage during the altercation or a subsequent expletive-laden rant. Fairfax Media has attempted to reach Mr Abbott for clarification.

"It wasn't a very effective headbutt, obviously, but it certainly was a headbutt. I pushed him away," Mr Abbott said.

"As you can see, I'm entirely unscathed. Nevertheless, it is more than a little disturbing that some supporters of same-sex marriage behave this way. I worry about the brave new world of same-sex marriage if this is how some of the people who are most enthusiastically working for it are behaving, with such bullying and intimidatory fashion

"There is no doubt that there has been some ugliness as part of this debate, but I regret to say that nearly all of it seems to be coming from one side and that is the people who tell us that love is love.

"Well, I'm not sure that love is exactly love. Certainly there are many different kinds of love and there is not much love coming from some of the 'yes' quarters towards people who have the temerity to disagree."

Mr Abbott rejected suggestions he might require police bodyguards in the wake of the incident. His Australian Federal Police protection ceased at last year's federal election.

"I'm not asking for protection. I think it is a great thing that Australian politicians mix freely with the people," he said.

Mr Turnbull said such questions were matters for the AFP.

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