Police resources are being spread thin as hundreds of officers are assigned to mass protests over conflict in Gaza, costing states upwards of $1 million per rally.
Up to 100,000 demonstrators gathered across Sydney and Melbourne to call for an end to the war between Israel and Hamas on Sunday.
NSW Premier Chris Minns revealed the bill for policing a major protest such as the recent pro-Palestine and -Israel rallies was "in excess of $1 million", although he said the measure was necessary to protect public safety.
Supporters have held regular rallies in Australia's major cities drawing crowds of thousands for the past five weeks since Hamas attacked Israel, killing more than 1000 people and taking hundreds hostage.
Israel has responded with retaliatory strikes and a ground invasion, which Palestinian officials say have killed more than 11,000 Gaza residents.
Up to 900 officers have been deployed to attend some of the larger protests and Mr Minns on Monday said police cost was an "enormous amount of money".
When asked whether the $1 million price tag represented an additional cost to taxpayers, the premier said the deployments were an operational issue for police.
"At some of those protests, upwards of 700 or 800 police officers (are) conducting overtime to police those protests," he said.
Police Association of NSW president Kevin Morton said the extra demand on officers was putting stress on an under-resourced force.
"Our commands are stretched across the board and when you factor in protests that creates an additional layer on that resourcing strain," he said.
The NSW Police force is about 1500 officers under strength because of recruitment shortfalls.
Mr Morton said requiring hundreds of officers to manage major protests risked leaving other shifts vacant and called on the federal government to provide extra funding.
"The continual drain on those resources to man these protests is really concerning," he said.
Mr Minns said he did not think it was unreasonable for state governments to ask the Commonwealth for help in offsetting the costs of policing the protests.
In Melbourne, there were violent clashes on Friday night after a Palestinian business at Caulfield in the city's southeast was firebombed, although a major rally on Sunday was peaceful.
Victorian Deputy Premier Ben Carroll was unable to put a cost on policing the protests but confirmed extra resources had been allocated in and around Caulfield and near places of worship.
"We do not want to see again a repeat of what occurred on Friday night," he said.
A social cohesion cabinet sub-committee, led by Mr Carroll, will meet for the first time on Monday.
Mr Minns defended the need for a large police presence at protests, adding the officers were not solely there for crowd control.
"They're also in place to monitor NSW's strict rules in relation to hate speech and racial vilification, and largely that takes place on the ground during a protest," he said.
NSW Greens MP Sue Higginson said keeping people safe was core police work and there should be no compromise on the right to peaceful protest, regardless of the cost involved.
