Officers were called to Worcester Park railway station at around 10.30am today (September 30).
London Ambulance Service crews also attended and found a man on the tracks.
He was taken to hospital for treatment and was found to have sustained an injury to his shoulder.
Police are carrying out CCTV enquiries to locate a woman they want to speak to in connection to the incident.
It is believed she pushed the man before making off down the tracks before officers arrived on scene.
Detective Inspector Baba Adeyeye said: “This is a really concerning incident and it is a relief that the victim wasn’t more seriously injured.
“I’d like to reassure the public that we are working at pace to locate the woman involved and establish the full circumstances of what happened.
“As well as anyone who witnessed the incident, we’d like to hear from anyone who may have witnessed the woman’s behaviour at the station in the lead up to it, or seen her in the time after.
“She is described as white, with blonde hair, in her thirties and was wearing a grey coat and distinctive black bobble hat at the time.
“Anyone who witnessed the incident and hasn’t already spoken to police, or has information that could help, should text BTP on 61016 using the reference 189 of 30 September.”