He attacked her and attempted to rape her, but stopped when he saw a man walking along the footpath.
The assailant ran from the scene and the girl, who was unharmed, was able to get home and told her parents what had happened.
“We want to hear from people who saw anything near the scene,” said Bertil Rosenberg at Gothenburg police.
Police have carried out a forensic examination of the scene and say they have found ‘certain things’. However, they did not reveal what those were.
The man is thought to have been wearing dark clothes while the girl was dressed in pink. The attack took place between 1.20pm and 1.40pm.