The truck got wedged at the bridge in Dellingburn Street.
Sergeant Laura Stewart, of Greenock police, said: "We got a call at 2.40pm and we contacted the council and Network Rail.
"It was treated as high priority, cars were forced to drive around the lorry.
"It caused a bit of disruption."
Onlookers said the lorry driver eventually managed to free the vehicle by reversing out and was being spoken to by police at the scene.
Video by George Munro.