Two teenage girls have been taken into custody following the circulation of shocking video footage showing a 13-year-old girl being violently attacked at a Melbourne beach earlier this month.

Authorities apprehended the two 15-year-old girls after the young victim was reportedly assaulted near a restroom area adjacent to Mordialloc Pier around 1:30 p.m. on December 17.

The disturbing video captures the victim being stomped, kicked, and struck while she lay on the ground.

A man in his 50s intervened, putting a stop to the alleged attack, after which the two girls reportedly fled the scene, according to police statements.

The 13-year-old victim sustained minor injuries from the incident.

Following their arrest, the two teenagers were questioned by the police and subsequently released as investigations continue.

Investigators are looking to speak to anyone who witnessed the alleged assault or those with dashcam or CCTV footage near the scene.

Detectives would also like to speak to the good Samaritan who helped the victim.

The investigation remains ongoing. 

Police swarmed Mordialloc Beach over two days last week, when sweltering conditions saw hundreds of teenagers flock to the shore.

Police used capsicum spray on members of the crowd as they allegedly clashed with officers, throwing glass bottles.