"It looks like he's attempted to ignite a fire in the vehicle, we believe at this stage with a view to igniting those canisters with some sort of explosion, but that didn't eventuate", Commissioner Ashton said.
"But he wasn't someone we were actively monitoring to that level".
Police said he was a 74-year-old man who worked in the city, but did not release his name.
"At this stage we are encouraging people to go to those events and there will be additional police over the weekend". "When a firearm is the last resort, they're (police are) trained to shoot to kill, shoot to the body mass".
Police said then they believed he was an ISIS sympathiser and was planning an attack Melbourne's central Federation Square on New Year's Eve in 2017.
Commissioner Ashton also says there is no suggestion that Shire Ali was inspired by James "Dimitrious" Gargasoulas, who is now on trial facing six charges of murder after allegedly mowing down pedestrians in January 2017.
After putting out the fire in the auto, authorities found what Ashton described as "barbecue-style" bottles of gasoline inside the vehicle, which prompted authorities to call the bomb response unit to the scene. He was shot by police and died in hospital.
Authorities say Australia's vigilance has helped foil at least a dozen plots, including a plan to attack Melbourne at Christmas in 2016 and a plan to blow up a flight from Sydney to Abu Dhabi using a bomb disguised as a meat mincer.
Melbourne's Lord Mayor Sally Capp sought to reassure the public and praised the police for their swift response. He at that time produced a knife and attempted to attack the police officers.
A witness, Markel Villasin, told Australian Broadcasting Corporation radio: "Bystanders were yelling out "just shoot him, just shoot him".
"This is an evil and terrifying thing that has happened", Victoria State Premier Daniel Andrews said.
Police were initially called to an incident in Bourke Street, right in the heart of Melbourne, after reports of smoke and a auto in flames. Some cordons were lifted later, though the immediate crime scene would be sealed until Saturday, police said.
Video shot from the scene showed the frenzied attack that carried on for more than a minute, beginning with Khalif charging at two police officers, punching one through a vehicle window and lunging at them with a knife.