A man has been caught on CCTV attempting to rob a medical centre in Melbourne's north-west with two young children in tow.

Police said the would-be thief asked staff at the centre in Caroline Springs about its opening hours about 5:30pm on November 3.

They believed the same man returned to the centre an hour later, after it had closed, and gained access via an internal door to an adjacent business.

Security footage showed the man searching through drawers and breaking into a cash register while two children — a boy and a girl — followed him around.

It is believed nothing was stolen.

Police urged anyone with information to contact Crime Stoppers.