The incident is reported to have taken place at Dumbarton Central shortly before 8pm on Thursday, April 4.
Officers from British Transport Police (BTP) said a group of teenagers were reportedly seen running into the station towards platforms two and three.
The 15-year-old boy was then allegedly attacked and is said to have sustained injuries consistent with being stabbed.
He was taken to hospital but has since been discharged.
Three 15-year-old boys have been cautioned and charged in connection with alleged serious assault.
One of the boys was also charged in connection with the alleged possession of a bladed article and another with the alleged possession of an offensive weapon.
Police are urging any witnesses to this incident to come forward.
BTP can be contacted by texting 610016 or calling 0800 40 50 40 quoting reference number 701 of April 4, 2024.
Alternatively, information can be passed on anonymously by contacting Crimestoppers on 0800 555 111.
