Tony Abbott has criticised the "disgraceful behaviour" of protesters after violent scenes erupted at his Sydney fundraising event on Friday night.

Several hundred protesters outside the event in Redfern confronted invited guests, including Mr Abbott's sister Christine Forster, whose jacket was ripped as she struggled through the crowd.

Ms Forster was forced back from the entrance until police formed a ring around her and pushed their way through the crowd.

Mr Abbott criticised the actions of protesters and defended his sister on Twitter on Saturday morning.