No one was injured in Tuesday night’s blast which destroyed a car parked outside a mosque and Islamic college in the Perth suburb of Thornlie.
“It is believed an accelerant was used to start the fire,” Western Australian police said in a statement, adding that three other vehicles were damaged in the incident.
“Anti-Islamic graffiti was located spray painted on a wall associated with the college, near the damaged vehicles.”
The mosque’s Yahya Adel Ibrahim said the community in Perth had been visited “by hate” but would not retaliate by “hating and playing blame games”.
“This, undoubtedly is a criminal act of hate, but it is the act of a person or group not the greater whole,” he said on Facebook.
“Despite what just transpired, everyone stayed to finish their prayers, refusing to give into the terror that had just occurred.”
Anti-Islam sentiment became more prominent in Australia last year as concerns mounted over homegrown extremism and citizens travelling to Iraq and Syria to support jihadist groups.
But Turnbull, who faces a general election on Saturday, said Australia had a fundamental foundation of mutual respect.
“I deplore and I cannot condemn strongly enough any attacks of that kind,” he told radio station 6PR.
Australian Islamic College executive principal Abdullah Khan said while the attack came as a shock, he had been reassured by the support from the community.
At the last national census in 2011, Muslims made up less than three percent of the overall Australian population of 24 million, with the overwhelming majority of the country identifying as Christian.