Prime Minister Tony Abbott is deeply concerned about the threat of “lone wolf” terrorism but has again urged Australians to remain calm.

The Australian Defence Force has warned personnel to be cautious when wearing uniforms in public, following an alleged attack on a 41-year-old officer in Melbourne.

The assault came days after the stabbing of two police officers by 18-year-old terror suspect Numan Haider, who was shot and killed.

• New laws to increase ASIO spying powers
• ‘Light on the hill’: Abbott addresses UN

Islamic State has ordered followers to attack non-Muslim Australians.

Mr Abbott said he was concerned about the threat of terrorism domestically but was confident in the ability of police and security agencies.

“People should go about their normal lives because that’s what terrorists are trying to do is scare us out of being ourselves,” he told Seven Network from New York.

The prime minister held wide-ranging talks with Iraqi counterpart Haidar al-Abadi on the sidelines of a special meeting of the UN General Assembly in New York.

About 600 Australian troops are assembled in the United Arab Emirates awaiting deployment to Iraq to help the multi-national effort to combat IS (also known as ISIL).

Mr Abbott said Mr al-Abadi welcomed Australia’s contribution to what had become the “world’s fight”.

He also left the way open to joining air strikes on IS in Syria, but said that was legally more tricky.

“Morally there’s little difference between ISIL, this death cult, on one side of the border to the other,” Mr Abbott told ABC radio.

Terror suspect Numan Haider, who was shot and killed by police. Photo: Getty

“But legally there’s a world of difference between operating inside Iraq in support and at the request of the Iraqi government and operating in Syria which is largely ungoverned space with a regime that Australia doesn’t actually recognise.”

The first part of anti-terrorism law changes passed the Senate on Thursday and will be sent to the lower house next week, where their passage is all but guaranteed.

The laws beef up the domestic spy agency’s powers and have bipartisan support.

Members of about 250 mosques around the country will unite on Friday to denounce violence overseas and condemn the IS order to attack Australians.

Mr Abbott reminded Australians the fight against IS was not linked to religion but rather to crime and terrorism.

He warned Australians not to inflame tensions within communities.