Security cameras have captured the moment a young couple became the victims of a serious assault while drinking with a group of people at a karaoke bar in Melbourne's CBD.

CCTV of the sickening attack has been released in an effort to track down those responsible for the bashing that left a 25-year-old man unconscious, and his 23-year-old girlfriend bruised and battered.

The pair were drinking at the Music Box bar on Elizabeth Street just after 1am on January 11 when three young men began punching and kicking the male victim.

He fell to the ground - unconscious almost immediately - before his girlfriend tried to intervene and stop the group from repeatedly stomping on him.

Police are searching for a group of men and women who kicked and stomped on a couple in a Melbourne karaoke bar. (Victoria Police) (Victoria Police)

Eventually the three men retreat, but when the female victim shoves one of the attackers in the back, he turns around and grabs her by the hair and pushes her away.

The next clip released by police begins just 10 seconds later, however by this stage the female victim is on the ground as one of the men repeatedly stomps on her head and shoulders.

Two men, believed to be staff at the karaoke bar, can be seen trying to restrain a number of the attackers, but a female offender who had previously been watching stands up and pushes her way through to kick the female victim.

The female victim then tries to kick one of the men while being held back by a male staff member, but a second attacker steps in and pulls her by the hair before throwing her to the ground.

One of the male attackers at the Melbourne karaoke bar can be seen grabbing the female victim by the hair before throwing her to the ground. (Victoria Police) (Victoria Police)

He and the female attacker can then be seen repeatedly punching and kicking the female victim.

Victoria Police detectives have released the video in an effort to track down the men and women in the security footage.