Mr Abbott earlier urged moderate Muslims to join the "Team Australia" fight against locally-bred extremists.
"What we need to do is to encourage the moderate mainstream to speak out," he told Macquarie Radio.
He was also asked about reports that shops in Sydney's southwest were flying Islamic State flags despite the group being listed as a terrorist organisation.
"I don't know what the legal position is, but frankly, the only flag that should be flying is the Australian national flag," he said.
"If people want to fly other flags - a corporate flag for instance - fine, but the Australian national flag should always be part of it."
