Gatecrashers at a birthday party in Sydney's east have punched and stomped on a 16-year-old boy, causing serious facial injuries.

Police say six to eight uninvited males entered a home in Matraville on Friday night that was hosting a 16-year-old's birthday party.

Police attend the scene of the party and attack in Matraville. Credit:Screenshot, 7 Network

After refusing to leave, they punched a 59-year-old man in the face and assaulted a 32-year-old security guard, according to police.

Other guests became involved and a 16-year-old boy, who was a guest at the party, was punched to the ground where his head and neck were stomped on before the intruders fled.