A 33-year-old man has been arrested by police after the bomb squad was called to Melbourne's CBD, where some buildings were put under lockdown.

Several trams were diverted from parts of Collins Street shortly before midday on Wednesday, and some workers in buildings nearby were told to stay inside.

In a statement, Victoria Police said the incident was not terror related and there was no immediate threat to the community.

Detectives will interview the man in relation to an ongoing Arson and Explosives Squad investigation, police said.

The Bomb Response Unit could be seen conducting a safety check on a white hatchback in Collins Street.

The police operation occurred outside a local bank, but police said the bank was not involved in the incident.