Protesters in Melbourne want Australians to use whatever means necessary to close the "torture camps" on Manus Island.
Days after shots were fired at the Papua New Guinea detention centre, about 150 protesters gathered in Melbourne to call for it to be closed.
"We should defend these refugees using whatever means necessary," Tamil Refugee Council spokesman Aran Mylvaganam told the crowd on Monday.
Watch: Scenes from Melbourne's protest
"Our government will not do it because this is what they wanted to see.
"They want to torture these refugees so that others who are waiting to flee their countries will not choose to come here."
Mr Mylvaganam called on Australians and the trade union movement to "lead the fight back" and close what he called torture camps.
"Your silence is costing lives," he said.
As many as 100 shots were reportedly fired into the Manus Island camp on Good Friday, according to Iranian journalist Behrouz Boochani, who is being held inside the compound.
Photos purportedly show bullet holes in detention centre buildings and a video claiming to be of the incident shows a white 4WD drive away as shots ring out.
But the Department for Immigration and Border Protection only confirmed one asylum seeker was hit by a rock and shots had been fired into the air by military personnel.
Papua New Guinea authorities are investigating the incident, according to a spokeswoman for the department.
The Manus Island detention centre is due to close on October 31.
Immigration Minister Peter Dutton says those refugees who aren't taken under an agreement with the US will settle in PNG, while non-refugees will be sent back to their home country.
Watch: Video from the centre of the suspected violent attack
