An officer has allegedly been "king hit" after trying to break up a large gathering in Melbourne's outer west.
About 50 people were congregating at a recreational area in Harkness on Tuesday afternoon in breach of the city's stage four lockdown rules.
Police attempted to disperse the crowd with a warning before allegedly being spat at.
When they tried to arrest a man, five to 10 people set upon them.
One of the officers was twice punched in the back of the head, police allege, and later treated for non-life-threatening injuries.
Deputy Commissioner Rick Nugent described the attack as a "king hit".
"Some of the behaviour is just disgraceful," he told reporters on Wednesday.
"It's really poor conduct towards police who are doing all they can to try and support the community as we make our way through this pandemic.
"It's still happening too often. We shouldn't be subjected to that but the reality is that it's happening."
He said four members were injured in the attack, with most suffering scratches and grazes.
Two males have since been charged with assault police and affray.
A Brookfield teenager has been remanded to face children's court at a later date, while a 23-year-old Brookfield man was bailed to appear before Sunshine Magistrates' Court next year.
Three other people are expected to be charged on summons with hinder police and COVID-19 breaches.
The investigation is far from over, Mr Nugent said, with police working to identify the rest of the group.
Australian Associated Press