The 54-year-old was working at West Ham station as a ticket inspection was carried out.
After asking a passenger about his ticket, the man approached ran off and was followed by the Tube worker onto a Jubilee line platform where an altercation ensured.
The staff member was then “barged” by the man, and the pair both fell onto the tracks before the other man ran off down the tracks, police said.
Officers said the victim was treated for a “laceration to his head” and an injured hand after the incident at about 2pm on Thursday.
Investigating officer, DC Dean Percival, said: “This was a serious and unprovoked assault and I am looking to speak with anyone who may recognise the man in the CCTV images. I believe he may have essential information that could help us piece together what happened.
“Likewise, I would also like to hear from anyone who witnessed this incident. I am conscious that there was a number of individuals on the platform at the time who witnessed what happened.
Anyone with information should call 0800 40 50 40 or text 61016, quoting reference number 271 06/07/17.
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