The Manchester City fan was confronted by a group of men while travelling on the train between Leeds railway station and London Kings Cross at around 10.40pm.
Police said the supporter was verbally abused by one member of the group, before a second man pushed him in his chest.
The group of men left the train at Doncaster.
Investigating officer, PC Saleh Ali, said: “I am keen to speak to the two men in the CCTV images as they may have information which could help with the investigation.
"I would also like to speak to anyone who may have witnessed this incident. Everyone has the right to travel on the rail network without fear or intimidation and are working to find the people responsible for this assault and bring them to justice.”
The altercation took place on April 23.
Anyone with information is asked to contact British Transport Police on 0800 405040, or text 61016 with reference 160 30/05/2017.