The incident happened on Tuesday, 3 January on a route 56 bus that was travelling on Essex Road, N1.
The 61-year-old man, who has learning difficulties, was approached by three youths, two males and one female.
One of the youths started to harass him and when he stood up to try and leave, the group began to punch and kick him.
The victim called out for help and the three ran off leaving the man injured.
The victim was left with two black eyes and has been left very distressed as a result of the assault.
Any witnesses or anyone with any information is asked to call the police on 101 or contact via Twitter @MetCC. Please quote CAD 4128/03JAN
To give information anonymously contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org.
