A protest against Prime Minister Tony Abbott at the University of Adelaide turned violent last night, with several people injured and a teenage girl taken to hospital after mounted police were called in.

Hundreds of people had gathered to express anger about issues including planned changes to university fees, policy on asylum seekers and marriage equality, while Mr Abbott delivered the Sir John Downer oration.

After several hours of peaceful protesting some people pushed over a fence that had been erected around the lecture theatre.

Mounted police were brought in to push the crowd back.

Protester Byron Stone says he was knocked to the ground by one of the horses.

"I didn't think they'd try to go through us like that so I stayed, and I got knocked over," he said.

"I fell down and then I was pretty scared.

"I ended up curling up as much as I could, but I couldn't curl up quick enough to get my left arm in, so it got trodden on.

"I've got some horse prints on my arm... and my friends say I have another one on my shoulder."

A teenage girl was also injured and was taken away by ambulance.

A tense standoff between protesters and police officers continued for some time before the crowd dispersed.

No arrests were made over the scuffles.

Speaking on 891 ABC Adelaide the morning after, Mr Abbott said protesters were trying to "shout down" the Government.

"People are perfectly entitled to protest, but I don't think they are entitled to drown out other voices," Mr Abbott said.

Mr Abbott was asked if perhaps people were shouting because the Government was not listening.

"Tell me what they want to say to me and we'll have a discussion about it, but all they wanted to do last night was shout," Mr Abbott responded.