Demonstrators had blocked streets and forced the closure of several metro stops during the city's evening rush hour.
Anarchist group Black Bloc also joined the protest, shattering glass at banks, bus stops and traffic lights, and burning garbage to block streets yesterday.
In addition to tear gas, police used stun guns and pepper spray. They arrested 17 people, saying in a statement none of the detainees were teachers.
The city's public primary and preschool school teachers have been on strike for 46 day and reject the city's plan, which the union says will only benefit seven percent of the teachers.
The teachers are demanding negotiations be resumed on the proposal.
