A-League boss admits a small number of fans are problematic

The head of soccer's A-League has admitted there is a small group of fans who persistently cause problems after supporters lit flares and wore balaclavas outside yesterday's grand final between Sydney FC and Melbourne Victory.

While authorities have praised the majority of soccer fans who attended the game at AAMI Park in Melbourne, the behaviour of some supporter groups outside the event has been labelled "disappointing".

Police said a number of supporters acted aggressively towards rival supporters at a pub, prompting officers to use capsicum spray to break up the crowd.

A 20-year-old Miners Rest man has been issued with a penalty notice, while a 17-year-old Frankston youth has been charged with behaving in a riotous manner.

Several flares were lit outside the park, and photos have emerged of some fans wearing balaclavas or covering their faces as they marched to the football ground.

Police say this portrays "an image more aligned to that of criminals hiding their identities than to genuine football fans".

Head of the A-League Damien De Bohun says police have told him personally how pleased they are with how fans behaved at the match.

But he admitted the handful of fans who choose to misbehave outside of matches were a problem.

"It's a very small minority of persistent and problematic behaviour from a very small group of fans," he said.

De Bohun says A-League will continue to work with police and management at Sydney FC and Melbourne Victory to make sure these types of fans have no place in football.

Yesterday, 21 people were ejected from AAMI Park for poor behaviour and there were seven arrests related to possessing a flare, interfering with police, possession of drugs, and assault.

Anyone who lets off a flare inside a stadium will receive a five-year ban from the Football Federation of Australia.