Attempted abduction on Vic school trip

A boy on a school visit to Melbourne's aquarium has been the target of an abduction attempt.

The seven-year-old was standing with classmates in the foyer of Sea Life Melbourne Aquarium in the city centre when he was approached by a man who sought to coax him out to the street.

"He hasn't touched him but has gestured for the boy to come with him. He had a guiding arm behind the boy," Detective Senior Constable Darryn Syme said on Friday.

"This child was shocked and started walking with the man, but a nearby teacher who was supervising stood in front of both the man and child."

The man then quickly left the building and boarded a tram.

Police have security video of the incident, which occurred at 12.50pm (AEST) on April 10.

The man is described as tall, aged 50-60, balding with short grey hair and was wearing a dark-coloured jacket and suit pants.