Pro-Palestine and anti-war protesters have planned a third straight day of demonstrations outside the entrance of the Melbourne Convention and Exhibition Centre which is hosting the Land Forces weapons convention.
Police were out in force again early on Thursday, maintaining no-go lines near the convention centre ahead of visitors to the expo arriving.
Police Minister Anthony Carbines said peaceful protesters who were caught up in violence at the rally "only have (themselves) to blame".
"It would be naive to think that if you've got yourself caught up in troubles down there, then you have probably put yourself in the wrong place," Mr Carbines said.
"And I think they need to take responsibility for their actions."
Violent and chaotic confrontations between protesters and police broke out on Wednesday, with dozens of activists arrested.
Police returned fire with rubber bullets, tear gas and flash bang devices. (Con Chronis/AAP PHOTOS)
Wheelie bins were set alight and thrown towards police barricades, while horse manure, food-grade acid, glass bottles and baked bean can "missiles" were launched at officers.
Riot officers returned fire on the 1500 demonstrators with rubber bullets, tear gas and flash-bang devices.
Police said 27 officers were treated for minor injuries, while rally organiser Caroline Da Silva said there were eight to 10 times the number of activists injured in the melee.
Demonstrators vowed to nurse their injuries and regroup on Thursday.
"We are not deterred," Ms Da Silva said.
Many types of weapon are on display at the convention in Melbourne. (Joel Carrett/AAP PHOTOS)
Protesters say many types of weapons on display inside the convention centre have been used on civilians in the Gaza conflict.
"People are very angry about this expo. It's particularly on the nose given there's already very strong community sentiment about the genocide in Gaza," Ms Da Silva said.
Police Commissioner Shane Patton urged protesters to reflect on their conduct and to consider whether their actions would garner support for their cause.
"We will be prepared for any event for the duration of this this conference, but I hope it doesn't occur again tomorrow," he said.
More than 40 people were charged with assaulting, hindering and obstructing police. (Joel Carrett/AAP PHOTOS)
"If people come to protest - we urge them not to - but if they do, and they come and do so peacefully, happy days."
Premier Jacinta Allan said she was particularly concerned to hear some protesters had come from interstate.
"When you come ... to protest carrying rocks, carrying bottles and balloons filled with urine ... your intent is not to peacefully protest ... indeed your motives are exposed," she said.
Mr Carbines said protesters' behaviour on Wednesday was on a separate level to regular marches which have opposed the war in Gaza.
"So there's protest activity, then there's just bar brawls and thugs, and that's what we saw yesterday," he said.
Protesters confronted mounted police in Melbourne's CBD. (Joel Carrett/AAP PHOTOS)
Opposition leader John Pesutto called for police to have wider powers to move on protesters and compel them to remove face coverings, amid what he described as the "normalisation" of protest violence in Victoria.
He claimed current laws were complex, restricted to certain areas and protesters could find ways around them.
"Victoria Police need more powers and want more powers," he said.
Amid the violent scenes, a coalition of human rights groups have written to the Victorian government calling for the prohibition of explosive devices, pepper spray and police horses at protests, which they say is an unnecessary use of force.
Police arrested and charged 42 people with assaulting, hindering and obstructing police, arson and blocking roadways on Wednesday.
The activists will rally outside the offices of defence contractors Hanwha Defence and Elbit Systems before holding a vigil for Gaza.
