Senior Sergeant Anthony Bond says members of the public reported a vehicle driving up and down Cavell St and the surrounding area transmitting through a loudhailer that there was a level 5 tsunami warning in place and residents should move to higher ground about 9.30pm.
The vehicle was located at a Jackson St property in St Kilda and an 18-year-old man spoken to about the incident.
He has admitted to driving and playing loud music, but denied mentioning a tsunami, Snr Sgt Bond said today.
Police last night posted on Facebook that the incident was a hoax.
Inquiries were continuing.