"I firmly believe that if we don't stand up and say something when we see something unacceptable then we are tacitly accepting it," he said.

By just before 4pm on Tuesday the petition, which calls on Metro to call the officer to account for his actions and provide anti-violence training and workplace counselling to all ticket inspectors, had attracted more than 18,000 signatures since being created on Monday afternoon.

The footage of the girl being picked up by the officer at Flinders Street Station on July 31 and slammed to the ground after hitting an officer in the face, was released to Greens leader Greg Barber though a freedom-of-information request.

Mr A'Vard said he was horrified at the level of physical violence taken against a young person even if the ticket inspector was acting in self-defence.

"It was something I wouldn't expect to see in Melbourne. I definitely wouldn't expect to see a person of authority in uniform to be behaving in that way towards a teenager who was unarmed," he said.