Paris prosecutor’s office spokeswoman Agnes Thibault-Lecuivre confirmed anti-terrorism authorities are looking into the incident, which occurred on Monday morning in the town of Aubervilliers.
The assailant is at large, she said.
Police say the assailant attacked the teacher with sharp object such as a box-cutter or scissors.
It is unclear whether the teacher suffered injuries.
The incident comes as France remains under a state of emergency after the November 13 attacks by extremists linked to the Islamic State group that killed 130 people.