An off-duty police officer was in Harbour Street at noon when he observed the domestic assault.

The constable, who is attached to the Police Transport Command, immediately intervened, taking hold of the boy before they became involved in a struggle on the footpath.

Uniformed police who were patrolling the area came across the pair and arrested the teenager.

He was taken to Wollongong Police Station and charged with common assault and intimidation.

He was granted conditional bail to appear at a children’s court on April 4.