The 42-year-old was walking west along Princes Street, towards Rose Street, in Edinburgh at around 8.20pm and had just passed Princes Mall as she talked on her mobile phone.
She was then shoved in the back causing her to stumble, at which time the phone was stolen from her hand.
The victim saw a group of around eight males run past her and make off up West Register Street before being lost to sight.
Three women came to assist the woman and helped her contact police, who are now urging anyone who saw anything suspicious to come forward.
The suspects are all described as being white and around 15-years-old. They were all wearing tracksuit bottoms and hooded tops of varied colours.
A police spokesman said: “Fortunately, the woman was not injured as a result of this incident.
“Nevertheless, she was left very distressed at the theft of her phone and we are keen to hear from members of the public who were on Princes Street at the time and who can assist with our enquiries.
“We are particularly eager to trace the three women who came to the victim’s aid, but left before police arrived. They are urged to contact police immediately.
“Similarly, anyone who can help identify those responsible is also asked to get in touch.”
Anyone with any information can contact Lothian and Borders Police on 0131 311 3131, or the charity Crimestoppers in confidence and complete anonymity on 0800 555 111.