Western Sydney Wanderers have accepted full ownership for an incident involving a group of fans harassing a Sydney FC supporter before last weekend's A-League derby.
Video emerged on Tuesday showing a man wearing a Sydney FC shirt being hit by an object as a mob of chanting Wanderers fans moved past a Parramatta restaurant on the way to witnessing the Sky Blues' 1-0 win last Saturday night.
Police made a total of seven arrests for unruly behaviour on the night.
"Our club's got to take full ownership for this, and we do," executive chairman Lyall Gorman told ABC Radio on Tuesday.
"We don't stand for this and nor will we stand for it.
"It's not a part of a our brand in any shape or form and we'll do whatever we can with stakeholders to weed it out of the game."
Gorman said 14 supporters have already been banned from the game for at least five years during the club's inaugural A-League season, and predicts more to come.
"We've still got this minority hooligan thug element who will try and break those rules wherever they can," he said.
"If there's 30, 40 or 50 people we've still got to get out of this game we'll do everything we can to do it.
"Be assured: they will be banned for a very, very lengthy period from our game, let alone what actions follow through from normal legal due process."
Superintendent Robert Redfern from Parramatta Local Area Command said police are reviewing footage of Saturday's incident but no formal complaint had been made by the victim.
He said the 160-plus officers who were on duty during last weekend's match "clearly wouldn't be enough" for the Wanderers' next game.
"We will be looking closely at what happens for the next match and if we need more, we'll need more," Supt Redfern told ABC Radio.
A-League boss Damien de Bohun joined the chorus of condemnation of fans involved in poor behaviour.
"The sold-out crowd of nearly 20,000 provided a huge amount of colour, noise and theatre, and the overall behaviour was exceptionally good," said de Bohun in a statement.
"Those fans who disturbed the enjoyment of fellow fans with anti-social behaviour have no place in the game."