A West Australian country football league says safety at its junior matches has improved after escalating violence on the sidelines prompted a ban on unaccompanied children from attending. 

The Broome-based West Kimberley Junior Football League (WKJFL) has been employing security guards and locking the gates to the town's main football ground ahead of its Friday night matches.

Children without an adult are no longer permitted to enter the grounds after the season opener was marred by fighting and a series of assaults.

"It's the young teenagers that tend to want to come and use that environment to fight each other," league president Scott Hill said.

"It tends to be the young girls … fighting amongst themselves, but it spills over and makes it not a nice environment.

"That's escalated this year into threatened violence towards our committee members and [sports] representatives, even rock throwing at their cars."

Mr Hill said 28 unaccompanied children were turned away by security on the first night of the ban on April 26, and a further 25 the next week.

"Within that number there was going to potentially be the ones that would cause trouble," he said.

Mr Hill said the the level of violence had been "confronting."

A 14-year-old girl was given a six-month intensive supervision order for a sideline attack on another girl in May last year, with the violence described as "sickening" during her appearance in the Broome Children's Court.

The Friday night games are usually attended by about 1,000 spectators and 550 players.

"I'm very confident we've got it back to a safe environment," Mr Hill said.

"The families are enjoying themselves and the kids are running around on the sidelines kicking the footy."