Former prime minister Tony Abbott says he was shocked when a man wearing a "Vote Yes" badge assaulted him after requesting a handshake in a "sign of trust and peace".

Key points: Tony Abbott says a person wearing a Vote Yes badge was behind the incident

Tony Abbott says a person wearing a Vote Yes badge was behind the incident He says a handshake is normally "a sign of trust and peace"

He says a handshake is normally "a sign of trust and peace" Both sides of the same-sex marriage debate have condemned the violence

Mr Abbott is an outspoken supporter of the campaign against same-sex marriage.

He said the man approached him on a Hobart street last night, asked to shake his hand and then headbutted him before running away swearing and saying Mr Abbott deserved to be hit.

"It's a shock to have a fellow Australian seeking to shake your hand turn a handshake into an assault," Mr Abbott told reporters in Hobart this morning.

"Normally a handshake is a sign of trust and peace, it's a sign of two people wanting to deal openly and courteously with each other."

Tony Abbott said his minor injuries included a slightly swollen lip. ( ABC News: Selina Ross )

Mr Abbott said his injuries were minor and included a slightly swollen lip.

The attack occurred around 4.30pm, before Mr Abbott attended a Young Liberals cocktail party on Thursday evening.

Tony Abbott met with No vote campaigners while visiting Hobart. ( Facebook: Tony Abbott )

Prime Minister Malcolm Turnbull has contacted his predecessor to check on his welfare.

"We must have zero tolerance for that type of violence, or any type of violence on the street," Mr Turnbull said.

Violence on both sides of the debate

Sorry, this video has expired CCTV footage shows Tony Abbott walking before alleged headbutt (Credit: Sky News)

Mr Abbott said it was "more than a little disturbing that some supporters of same-sex marriage behave this way".

"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," he said.

Earlier this month, the godson of former prime minister Kevin Rudd was allegedly assaulted in Brisbane by a man who was tearing down rainbow flags put up in support of same-sex marriage.

In May, Qantas chief executive Alan Joyce had a lemon meringue pie launched at his face in a protest about his advocacy for same-sex marriage.

After he was dumped as leader Mr Abbott had police protection, but he says that ended after the last election and he won't be asking for it to be reinstated.

"I think it's a great thing that Australian politicians mix freely with the people. I think it would be a sad thing if that was ever not possible and certainly it's my intention to keep going about the things that I do."

Tasmanian police said they had spoken to several witnesses to the incident that occurred on the footpath in Morrison St opposite Custom's House Hotel, and urged the alleged attacker to come forward.

"What I do encourage is that the gentleman involved make contact with police," Commander Tony Cerritelli said.

"Similarly, if there are friends or colleagues of the offender who know something about it — again, we just want to deal with this in a professional and businesslike way, and if we can resolve this in the simplest and least public way, that would be good."

The alleged attacker is described as being approximately 40 years old, of medium build, with spiky sandy, strawberry-coloured hair and facial piercings.

"He was probably in the company of another male who did not approach Mr Abbott or participate in the alleged assault," Commander Cerritelli added, saying police were working hard to obtain more CCTV footage from the area.

Pro- and anti-SSM camps condemn violence

The incident was widely condemned by both sides of the same-sex marriage debate.

Tasmanian senator Eric Abetz — an outspoken critic of the same-sex marriage push — told ABC News Breakfast the incident highlighted "yet again another example of the ugliness of the Yes campaign".

"Their slogan of 'love is love' is unfortunately shown in practice to be intolerance, not wanting people to be able to have their point of view," he said.

Sorry, this video has expired Eric Abetz condemns alleged headbutt attack on Tony Abbott

Alex Greenwich, from Australian Marriage Equality, said there was no place for violence in the same-sex marriage debate.

"Marriage equality is about fairness and equality and we expect everybody to be treated with equal dignity and equal respect," he said.

"Australians expect everybody engaged in this issue to do so in a respectful and dignified way."

Opposition Leader Bill Shorten also condemned the incident and said he rang Mr Abbott to convey his concern.

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Prominent same-sex marriage campaigner Sally Rugg tweeted "all violence happening during this plebiscite is abhorrent, including alleged assault on Tony Abbott".