A mass brawl broke out when up to 50 youths gatecrashed a wedding reception in Perth's southern suburbs.

Bricks were hurled through the windows of Point Walter Cafe in Bicton as the youths tried to force their way into the venue on Saturday night.

Several of the guests who were either hit by the bricks or injured in fights were taken to hospital for treatment.

The incident began when a number of youths were refused a cigarette by one of the guests attending the wedding reception.

The group returned later with more people and once again asked for a cigarette from a guest and were again refused.

An altercation took place between the guest and the youths, which escalated when more wedding guests came outside to assist the man and more youths arrived at the venue.

Police said up to 60 people were involved in the trouble.

Seven guests, including four men and three women, were injured in the violence and a number of them were treated at Fremantle Hospital.

The offenders, who were described as mostly dark-skinned males aged about 16 to 22 years old, fled the scene before police arrived at 9:10pm.

Police have been reviewing CCTV vision of the incident.