Two Aussie tourists took it upon themselves to get justice after seeing a man urinating and waving his genitals in front of their female friends.

Nirvan Lane and Asher Ghannoum began fighting the unknown man outside a bar in Queenstown after one of the women they were travelling with took offence.

But their bid for justice ended in the Queenstown District Court, with Lane pleading guilty to common assault and fighting in a public place, while Ghannoum was charged with assault with intent to injure.

Judge Russell Walker said starting a fight was not a normal reaction to being offended.

"They call the police. They don't physically assault that person. It's that simple," he said.

"The locals who live here in Queenstown are heartily sick of violence in the street after people have been drinking."

The group were partying in Queenstown on 23 July when one of the women in the group took offence to a man urinating in public right in front of them.

The man then waved his genitals around, causing further offence.

The court heard Lane approached the victim and, without any warning, initiated a physical confrontation by punching him. A fight ensued.

Another member of the public saw the commotion and while attempting to break it up, he was punched by Lane.

Ghannoum saw the fight happening and jumped in, punching the victim then kicking the victim when he was on the ground.

Lawyer DeAnne Nicoloso said the two convictions for Lane will "have a punitive effect on him".

The 20-year-old is a full-time uni student studying commerce and cyber security in Sydney and working 20 hours a week at Bunnings.

Meanwhile, Ghannoum is an electrical apprentice.

"He is very remorseful."

The pair would be returning to Australia later in the week.

Walker took into account the pair had no criminal history in New Zealand or Australia.

Lane was fined $750 and $152 in court costs for common assault and for fighting in a public place, he was convicted and discharged.

Ghannoum was fined $1250, with court costs of $250.

Violence, especially involving alcohol, is not a new problem in the tourist town.

Earlier this year, 26-year-old Mattheus Heimer was sentenced to nine months' supervision after he slapped a woman and pinned her down inside the local McDonald's while he was on a drinking bender.

Meanwhile, at the sentencing of Braden Jane, who assaulted a man outside an Arrowtown pub, Judge Mark Williams said there was too much alcohol-related violence in the tourist town.

"There needs to be a message that violence in Queenstown will not be tolerated," he said at the hearing.

Destination Queenstown Lake Wānaka Tourism chief executive Mat Woods said it was "disappointing to see international visitors come into our community and act violently".

"Our hospitality sector works hard alongside Police, licensing authorities and the wider community to promote responsible behaviour and ensure the town remains a safe place for residents and visitors alike.

"Queenstown Lakes is renowned as a safe and welcoming destination, hosting nearly three million visitors a year. The overall crime rate in the district remains below the national average and is declining year on year, making it an overwhelmingly safe place to live and visit."