A 15-year-old boy is fighting for life after being bashed with a metal pole in Melbourne.

Police were called to a home in Cranbourne North after a group tried to gain entry about 12.30am Thursday morning.

The victim and a friend went outside to confront the group when he was viciously struck in the head with a metal pole.

Victoria Police said he suffered life-threatening injuries and was rushed to hospital where he remains in a critical condition.