The victim declined and Desai drove off, but he quickly stopped his truck again, this time opening the door and telling her he would take her home.
The teen pushed the door and ran off, noting Desai's vehicle registration, before she contacted triple-0.
Representing himself yesterday, Desai, who pleaded guilty to one count of stalking/intimidation, said he didn't know the teen before the incident and begged for forgiveness for his actions.
Magistrate Les Mabbutt said the matter was serious, noting public concern over strangers approaching children.
Desai will front Wollongong Local Court on October 30 for sentence.