The British Transport Police (BTP) were called to Gipsy Hill station on the Crystal Palace line just before 7.45pm on February 6 to reports of an altercation.
It was reported that a man had barged into a group of young girls.
The man went on to racially abuse one of the girls and punched her three times in the face when she challenged him.
When the rest of the girls tried to stop him, the man assaulted them.
Detectives are now investigating the assault and have released images of a man they believe could have information that could help their investigation.
Anyone who recognises the man or has any other information is asked to contact the British Transport Police by texting 61016 or by calling 0800405040 quoting reference 726 of 06/02/2025.
People can also contact Crimestoppers anonymously on 0800 555 111.
