Thousands marched through Sydney on Saturday to demand an end to lockdown measures, with smaller demonstrations taking place in Melbourne and Brisbane.
At least 57 people involved in the Sydney protest have been charged, while more than 500 have been fined.
On Sunday, New South Wales (NSW) premier Gladys Berejiklian said the protesters "should be ashamed".
"Millions and millions of people across our state are doing the right thing, and it just broke my heart that people had such a disregard for their fellow citizens," she told reporters.
The state recorded 141 new infections on Sunday, the second-highest daily increase of the year. There are fears of a further rise in cases following Saturday's protests.
Authorities in NSW are expected to extend the current lockdown, which is set to end on 30 July.
Some 13 million Australians are back in lockdown after state governments re-imposed restrictions in recent weeks to combat the highly contagious Delta variant, which has driven up cases across the country.
Fewer than 14% of the population have been fully vaccinated, a far lower percentage than most European countries and the US.