An autistic teenager who was bashed by a group of five thugs in Melbourne's west on the weekend says he is now too scared to leave his own house after the horrifying attack.

In an interview with radio station 3AW, the 17-year-old's mother said the youths, who she believed were Sudanese, approached her son while he was travelling on a bus at Tarneit on Saturday.

He said the youths demanded his mobile phone and sneakers.

"When he wouldn't hand them over, they attacked him," his mother told 3AW.