The 24-year-old is expected to be charged with drugs and weapons possession, but the charges are not linked to the auto attack.
Mother of driver allegedly responsible for Thursday's horror arrives at court swinging her handbag.
The streets outside Flinders Street Station were busy with commuters and holiday shoppers when the SUV rammed into pedestrians.
Eleven others remain in hospital, three of who are in critical conditions, following the incident outside Flinders Street station on Thursday afternoon.
Senior Constable Singh said the motive remained under investigation and more charges could be added. Another man who was not in the vehicle was also arrested at the scene.
Saeed Noori, 32, of Heidelberg West, briefly appeared in the Melbourne Magistrates Court on Saturday wearing a grey t-shirt, charged with 18 counts of attempted murder and one count of conduct endangering life. Mr Noori did not apply for bail.
He also ordered that Mr Noori be seen by a nurse for physical and psychiatric issues.
Mr Noori is an Australian citizen who came from Afghanistan via a refugee program in 2004.
'He ran, was grabbed, and arrested, ' Mr Patton told 3AW.
Another witness, Cameron Von Borstel, said he assumed a auto had crashed into a tram when he heard a loud bang from the direction of Flinders Street.
Victorian Premier Daniel Andrews called it a "terrible, evil cowardly act", but said there was no need to change the state's threat level.
"He has said, in a number of what the police are describing as utterings, he has said that he attributed his actions to perceived mistreatment of Muslims", the PM said.
Cold winds, 3 to 5 inches of snow on Christmas Eve
In the small area of upstate NY that's between New England and the Great Lakes, estimates range as high as 24 inches of snow. The National Weather Service has issued another winter weather advisory that will be in effect from 5 p.m.
"I've got a firm belief that what he (allegedly) did on Thursday night was a deliberate act", he told reporters.
"We heard this noise and we looked up, then we just heard, 'bang, bang, bang, ' and people flying everywhere", said Jim Stoupas, who owns a doughnut shop nearby.
"Bodies were just thrown into the air", eyewitness John said.
Police have said they do not believe the attack terrorism related and that Mr Noori has mental health issues.
Crowds at Melbourne's Carols by Candlelight and Boxing Day Test can expect a "highly-visible" police presence as well as at popular spots as Federation Square and Melbourne Central, transport hubs and the MCG. We haven't ruled anything in or out and our counter-terrorism command continues to obviously assist crime command in this investigation.
"We have nothing to indicate this was a planned attack at this time", he told reporters.
Prime Minister Malcolm Turnbull has reiterated that police have found no terror links to the driver involved in the Flinders Street crash.
Nine of the victims of the crash were foreign nationals, among who was a 25-year-old Irish woman who is in a stable condition in hospital.
An off-duty police officer, credited with restraining the driver, was also hospitalised.
CCTV footage shows the white auto pull out of traffic and onto the tracks, accelerating into the crowd of Christmas shoppers before crashing into a bollard.
Police said nine foreigners were among the injured, including from South Korea, China, Italy, India, Venezuela, Ireland and New Zealand.