The 23 year-old was in the Spider Park play area, off Berryhill Road, at about 7.15pm on Wednesday.
She had been talking on her phone when someone took hold of her from behind, pulled her hood over her face and pulled her to the floor.
The dog began barking at her attacker who then fled the scene and ran towards Berryhill Road.
There is no definitive description of the suspect as the woman’s face was covered and the area was in darkness.Police have been patrolling the area and making local enquiries in an effort to establish whether there were any witnesses.
DS Pete Shaw said: “This was a terrifying ordeal in an area well used by people in Mansfield.
“If you saw anything suspicious or anyone acting suspiciously in the area, in particular if you saw someone rushing out onto Berryhill Road, please get in touch. Something you may think is insignificant could prove vital to our investigation.
“Similarly I want to appeal to anyone who has CCTV in the area which may have picked something up to review the footage and contact us if there is anything of note.”