"The Principal Secretary of the Urban Development Department (Nitin Kareer) has been asked to conduct a probe into the cause of fire and submit a report within 7 days," Patil told PTI.
Asked if prima facie there was any suspicion of foul play, Patil said truth will be out in the report.
He added that safety and security of passengers in all modes of transport remain the top priority of the government and that there will be no compromise on it.
Two coaches were affected in the incident.
Currently, the city has one monorail line, which runs along a nine-km route, covering seven stations, from Chembur to Wadala. The trains run from 5 am to midnight daily.