John Howard said on Thursday that recent incidents, in which churches were vandalised and a church hall was burned to the ground in a fire described by police as suspicious, were "particularly repugnant".
"Attacks on churches, attacks on any places of worship, are to be utterly and unconditionally condemned," he said.
"What we have to try to do is calm everybody down, change the law where necessary, support the police and then reflect in the weeks ahead as to what some of the fundamental reasons are.
"Maybe there were warning signs around that have been ignored that shouldn't have been ignored, but let's not do that in the heat of current events."
He backed new legislation giving police in the state of New South Wales new powers to deal with riots.
The lower house of the state parliament passed the new legislation, which will enable police to "lock down" areas of unrest, in an emergency session on Thursday after being recalled from its summer recess.
Tensions between Australians and
Arab immigrants have boiled over
The laws were expected to be passed by the upper house later in the day and could be in effect by nightfall, officials said.
Dozens of people have been injured and arrested in racial violence since Sunday, when a mob of whites attacked people of Middle Eastern appearance at Cronulla beach in Sydney, sparking retaliatory rampages.
Morris Iemma, the New South Wales state premier, said that the government was determined to give police the powers they needed to quell the unrest.
"Louts and criminals have effectively declared war on our society and we are not going to let them undermine our way of life," Iemma told parliament.
Under the laws, police will be able to cordon off areas and prevent vehicles from entering them, stop and search people and seize vehicles and mobile telephones for up to seven days.
Police will also be given the power to close licensed premises and to declare alcohol-free zones.
Howard called church attacks in
Australia 'particularly repugnant'
The maximum sentence for rioting will be increased from 10 to 15 years, among other tougher jail terms for assault during public disorder.
Iemma said the new laws were designed to protect the silent majority of law-abiding Australians from hooligans and thugs.
"As long as these thugs, these hooligans, these hotheads and these criminals disrespect the law, as long as they refuse to show respect and responsibility, these powers will be used to the fullest extent," he said.