Protester lunges at Julie Bishop's car

An anti-government protester has lunged at Foreign Minister Julie Bishop's car as she left a C20 summit in Melbourne.

The minister was leaving the summit after giving the keynote speech when the protester holding a banner hurled himself at her government car as it was driven away from Melbourne University on Friday.

The man was arrested in the middle of the street, with a group of a dozen protesters chanting "This is a peaceful protest" and then "Let him go" as he was being handled by police.

The protesters were airing concerns about job losses and university fees.

Ms Bishop was also targeted by protesters at Sydney University in May.

The deputy Liberal leader had to be ushered by security from Sydney University after being mobbed and heckled by about 20 students protesting against proposed cuts to education in the federal budget.

Ms Bishop on Friday delivered the opening address to the C20 summit, the first of the lead-in summits before the G20 leaders' meeting in Brisbane in November.

The University of Melbourne building where the summit was taking place was guarded by police at the entrance and temporarily locked while the protesters were waiting outside.

While people were allowed to exit the building, no one was allowed to enter until Ms Bishop left the building.