"Police are looking for the male.
"However, there is no decent description and police are working to identify possible suspects,'' the spokeswoman said.
"No similar incidents have been reported and anyone with any information is asked to call Dunedin Central Police Station.''
CIB is investigating.
A dog unit was sent to the scene and the girl's jacket was found further down the steps, towards Forbury Rd, but no sign of the offender was discovered.
"She was shocked but not injured,'' the spokeswoman said.
Easther Cr resident Michael Lowe said she was alerted to the attack when she heard screaming.
"All I could hear was screaming,'' she said.
She tried to help the girls, but all they wanted was to find the attacker and the teen's jacket.
"We asked if the guy had any other intentions and she said, `No, I don't think so','' Lowe said.
"It was weird.
"This is a very quiet street and things like this don't normally happen.''
Anyone with information should contact Dunedin police (03) 471-4800 or Crimestoppers 0800 555-111.