AUCKLAND, Feb 28 - She ran into her school and told a teacher about the incident, which happened in St Heliers between 8am and 8.20am on Tuesday.
Detective Inspector Scott Beard says the girl was not injured, but is shaken by what happened.
He says police are carrying out area inquiries and are seeking to get and review available security camera footage.
Officers will also be carrying out extra patrols before and after school for the rest of the week to reassure the community.
Beard says the man followed the girl on St Heliers Bay Road and, when she arrived at her school, he came up from behind her and grabbed her.
He says it is not known if the man had a vehicle nearby.
The man is described as having light brown skin and brown/grey hair with a bald patch on top.
He is possibly in his 40s, tall and of solid build, and has a cut on the top of a wrist and a piercing in his right eyebrow.
He was wearing a blue top with short sleeves and black pants, possibly track pants.