The teenager was one of three young people picked up by police responding to the attempted car theft in Market St last night, Acting Senior Sergeant Simon Reay said.
A 12 and 14-year-old female were arrested along with a 13-year-old male.
"They resisted arrest and the 14-year-old assaulted a police officer," he said.
She was charged with five offences and the other two were released back to Oranga Tamariki.
The police officer was not injured in the incident.