Police are investigating after the youngster was struck by an unknown man as she walked along Goldsmith Avenue, near Orchard Park, in Southsea, at about 3.30pm yesterday.
The girl had been walking home with a friend when the assault took place.
Hampshire police are calling for witnesses to come forward.
Anyone with information should called 101, quoting the crime reference number 44190106410.
For all the latest news, traffic and travel, what’s on, Pompey, sport and breaking stories visit The News’s website.
We will be bringing you all of the latest stories from across Portsmouth and surrounding area throughout the day.
If there is a story you think we should know about, you can contact us via our email [email protected] or via our social media channels – Facebook or Twitter.
Sign up for our WhatsApp service to get the latest news direct to your phone.