It happend near a ginnel off Stockwell Road between 3.35pm and 3.43pm on Wednesday (21 March 2018) as the girl was walking home from school.
The girl ran home and informed her parents about what had happened. They reported it to the police later that evening.
Police enquiries have been ongoing in the neighbourhood, including a trawl through CCTV and speaking to local residents.
There were potential witnesses nearby at the time, including a man on a mobility scooter. They have been urged to contact the police.
Officers are working with local schools to raise awareness about the incident.
Reassurance patrols are also being carried out in the area while the investigation continues.
The suspect is described as 6ft tall, slim build, short dark and grey hair, and he was wearing a checked top and baggy blue jeans.
Anyone who can help to identify the suspect or has information that could assist the investigation should call North Yorkshire Police without delay on 101, option 1, and speak to the Force Control Room.
Information can also be passed to Crimestoppers anonymously on 0800 555 111.
Please quote reference number 12180048511 when providing details about this incident