The Turnbull government is lobbying states and territories to beef up security in public places in the wake of the deadly Bourke Street rampage.
The prime minister wants to see more bollards along roads and footpaths across the country to guard against vehicle attacks.
"This is a very, very concerning vulnerability we have," he told Neil Mitchell on 3AW radio on Friday.
"Anywhere you have a large number of people together we need to be able to ensure as much as we can that it is not possible to get a vehicle into that place."
Mr Turnbull said there was generally good planning around big events such as New Year's Eve festivities.
"But when you're looking at pedestrianised areas in cities, you need to have a very hard-headed think about how you make it harder to get a vehicle in there."
He spoke of the role bollards played in the deadly Bourke Street attack, where five people died after a driver mounted footpaths.
"This criminal sought to turn into I believe it was Little Collins Street and wasn't able to do so because of bollards," Mr Turnbull said.
"Then of course he turned into and began his murderous assault in Bourke Street."
Counter-terror officials have been in talks with state and territories about hardening public security since deadly terror attacks in Nice and Berlin last year, where vehicles were used to cause mass injury.
"I believe more work has to be done in that area," Mr Turnbull said.
