Police believe a random stabbing outside a Melbourne shopping centre was related to mental health issues rather than terrorism.

A 44-year-old man was stabbed in the chest and neck outside Moonee Ponds Central shopping centre on Homer Street at about 4:35pm on Monday after getting into an argument with a 55-year-old man.

Police said the pair did not know each other.

The victim suffered minor injuries and was taken to hospital for treatment after helping to restrain the man until police arrived.

He was helped by passers-by and shopping centre security.

Cars drive down a street lined with shops and trees at night.

The argument and stabbing happened on the footpath outside the shopping centre. (ABC News)

After police arrived, the man shouted a phrase that prompted officers to call in the counterterrorism unit.

“This phrase was used after he was in custody, we do not believe the phrase was used during the offending,” Acting Inspector Raj Tillekeratne said.

“We have nothing to indicate that this is either religiously or politically motivated, so we’re just treating it like a random, isolated offending.”

A bald man in a navy police jacket over a navy collared shirt stands outside a brick police station at night.

Acting Inspector Raj Tillekeratne says there is no threat to the community after the stabbing. (ABC News)

Acting Inspector Tillerkeratne said the man had an extensive history of minor offending and mental health issues.

Investigators were waiting for an assessment by the Forensic Medical Officer before interviewing the man.

Acting Inspector Tillerkeratne said police were still investigating what the pair were arguing about.

He praised the bravery of the victim and passers-by who performed the citizen’s arrest.

“[The victim] is quite lucky. It could have easily have been worse than what really occurred.”