A wildlife park visitor has been accused of assaulting another man and threatening him with a knife after complaining that it was his turn to pat the koalas.

Police on Tuesday said a 34-year-old Para Hills man had been charged with aggravated assault and two counts of assault at the Adelaide Hills park on Saturday.

The visitors were waiting to pat the koalas when the 34-year-old man allegedly became aggressive and assaulted the victim.

"Two bystanders tried to intervene and were also assaulted, as was a staff member at the wildlife park," police said.

The man also allegedly threatened the victim with a knife, police said.

He has been bailed to appear in Mount Barker Magistrates Court on 5 March.