Four teenagers have been detained over the vicious bashing of a father of two at a train station in Melbourne's west this month.

The victim, Gary, 37, was at St Albans train station about 2pm on Friday, March 11 with his wife and two of his children, aged three and four, when he approached a group of men and asked them to "relax the language" and was allegedly attacked.

He required reconstructive surgery for injuries to his face.

Transit crime unit detectives arrested four teenager males over the alleged assault about 9am today.

Police said two 15-year-olds, one from Kings Park and the other from Taylors Hill, an 18-year-old and another teen from Hillside were being questioned over the attack.