Protesters face two separate fines if they attend an anti-lockdown rally at Melbourne's Shrine of Remembrance.
Apart from breaches of health directions, Victoria Police Assistant Commissioner Luke Cornelius said protesters also could fall foul of legislation governing behaviour at the Shrine.
The protest is planned for 2pm on Friday at the Shrine, with a Facebook post and makeshift signs hung above major Melbourne roads advertising the rally.
Mr Cornelius said the RSL and the Shrine have made it clear that any protest on the site is disrespectful to the memory of people who have served their country.
He said the Shrine legislation covered behaviour and how people are dressed, adding that anyone who refuse to obey police could be fined around $300.
While lockdown rules have been eased this week, Melburnians can still travel no more than 25km from their homes.
They also can be fined if they gather in groups of more than 10 from more than two households, and must wear masks as well as social distance.
Mr Cornelius said everyone, regardless of if they are protesting, going for a jog or having a picnic, could be subjected to police questioning to test each guideline.
"Whether you're protesting down at your local park, whether you're protesting at the Shrine, you must comply with the CHO directions about public gatherings," he told reporters on Thursday.
"Because if you don't, and we observe you in breach, we will hold you to account."
There were scuffles and several arrests last month as police broke up a protest at the Shrine.
Australian Associated Press