'How can you treat children like that?': Indigenous kids allegedly cable-tied

The 45-year-old allegedly restrained the children, aged 6, 7 and 8 years, in a driveway at 2.15pm on March 5 while waiting for police to arrive.

The man has been charged with three counts of aggravated assault and released on bail but experts are saying the problems with racism run deep in Australian culture.

Human rights advocate and lawyer Dr Hannah McGlade said vigilante justice aimed at tackling youth crime had the opposite effect. "It's making the issue of youth offending far worse," she said.

"We need to be doing smart justice not racist justice," the associate professor at Curtin University's law school said.

"We have a problem with racism in Australia and it hasn't been tackled or addressed adequately."

"There's a clear obligation of the Australian state under the UN Convention on the elimination of race discrimination. Without anti-racism strategies and laws to hold people accountable when crimes are committed, we're not going to see an end to this kind of racial violence," she said.

Commissioner for children and young people WA Jacqueline McGowan-Jones said she had been "contacted by multiple community members yesterday about this distressing incident".

"People are worried about the children, about possible vigilante action, and I would just like to encourage the community to remain calm in the wake of this alleged assault," she said.

"It is my understanding that the children were swimming in the pool of the vacant house and while full details are not yet available about why the police were called, we need to understand that these are young children and there is absolutely no excuse for such an overreaction.

"These children are aged six to eight and international research shows at that age - whether they have a disability, cognitive impairment or not - children are not able to fully comprehend the moral consequences of their actions."

Police said officers were working closely with the affected families and "acknowledge the challenging circumstances surrounding this incident".

Rowena, the mother of 6-year-old Margaret and her older brother Stuart, said she asked the man to let her children go, saying they would all wait for the police together.

"I had to stand behind the fence while he kept my children in the yard," she said to A Current Affair on March 6.

"My son was crying for water," the mother said.

"It's a disgrace, how can you treat little children like that?"

Dr McGlade said "these were children swimming on, no doubt, a very hot day".

"Children who are living in poverty, as many Aboriginal children are, their parents may not be able to afford for them to go to swim at the local pool," she said.

"It's time that we really live up to our ethos as a fair go nation and start making sure that swimming is something that all children can enjoy."