The incident happened at about 6.30pm on Tuesday 2 August when a nine-year-old girl and her friend were walking along the Wellway, Sunnyside Rotherham, when a man indecently exposed himself.
The man is also said to have made inappropriate comments towards the two girls.
Following an initial appeal for witnesses, officers have now released an e-fit image of a man they would like to speak to in connection with the incident.
He is believed to have been wearing a green and black Nike top and black tracksuit bottoms and was riding a mountain bike.
Do you recognise the man? If you know who he could be, or have any information about what happened, please call 101 and quote incident number 1044 of 2 August 2016.
Information can also be emailed to [email protected] or passed to Crimestoppers anonymously by calling 0800 555111.