The victim, identified as Rituja, was travelling in the ladies compartment of a Vashi-bound local train from Panvel late last night, police said.
"As the train was leaving Juinagar station the thief barged into the train around 11:45 pm last night. He robbed the woman of jewellery and tried to alight. The woman, having raised an alarm, attempted to stop the robbery but in the process fell down from the train," the official said.
Railway police said that a case had been registered against an unknown person under Sections 397 (robbery, or dacoity) and 307 (attempt to murder) among others of the Indian Penal Code (IPC).
The police said further investigations were on with personnel scanning the CCTV footage of the station to identify the accused.