A 12-year-old boy has been arrested over an incident in the Perth CBD last week in which a motorcyclist was knocked off his bike by a rope strung across Wellington Street.

Lawson Mills, 19, received rope burns to his neck in the incident when he was travelling home from his job as a waiter.

After walking over to confront a group of teenagers and children, he was allegedly attacked and had a glass bottle smashed over his head.

Mr Mills was treated in hospital overnight for whiplash, abrasions, rope burn and for a gash to the back of his head, which required around five staples.

Police tracked down the alleged offender after investigating CCTV vision.

The boy, from the eastern Perth suburb of Bayswater, has been charged with one count of wounding.

He is due to appear in the Perth Children's Court today.

Officers are hoping to arrest others involved.