Schools are still out in many parts of the country after two months of action.
The Peruvian Interior Minister Carlos Basombrio says he wants to restore calm after the teachers' strike over pay and conditions threatened to escalate.
Basombrio also tried to defuse tensions over comments made earlier this week by President Pedro Pablo Kuczynski, likening the teachers to the Sendero Luminoso or Shining Path guerilla movement.
Basombrio told a news conference, "The teachers of Peru are not terrorists, they are not senderistas, they want better wages, better conditions and the government is complying like the governments that preceded it, when there was enough money to do it."
However, he confirmed the president's decision not to negotiate with the radical unions that have led the mobilizations since a partial agreement reached on August 10 between the government and the main teachers' union — only a few hours after Education Minister Marilu Martens agreed to negotiate.
Pedro Castillo, who is now leading the movement, “shall be investigated for his political actions,” Basombrio added, as well as 18 other unionists, and alleged their links with terrorism.
In a televised message on Wednesday, Kuczynski refused to sit down to talks with some trade unions claiming they were linked to the guerrilla armed group.
The “indefinite strike” started on June 15 in Cusco, and was soon followed by other 12 regions across the country.
The union which started the action, Suter-Cusco, reached an agreement with the government on August 10.
Under pressure, the president eventually accepted some of their requests, ordering a pay rise starting in December.
Teachers' minimum salaries will be raised to US$616 per month — still less than their counterparts in neighboring Ecuador and Colombia.
But about 238,000 out of a total of 360,000 teachers did not go back to school, according to the Education Ministry.
The regions of Puno, Junín, Madre de Dios and Andahuaylas remain on strike.
Meanwhile, hundreds of teachers from the southern provinces of the country arrived in the capital Lima and started occupying the central San Martin Square.
The movement is divided between the main teachers' union, Sutep — historically controlled by the party Red Homeland.
More radical unions have emerged in the meantime, including the south-based Pukallacta and the National Committed of Struggle and Reorientation-Reorganization, or Conare, related to the controversial Movement for Amnesty and Fundamental Rights or Movadef.
The Movadef was created in 2009 in order to pressure the government to release political prisoners involved in the country's armed conflict.
The movement has rejected accusations of links with the Shining Path group, arguing that such claims are part of a strategy designed to stigmatize and criminalize its members, and deny their political rights.
Basombrio told lawmakers in June that “in his opinion, it is crucial that the members of the Movadef end up in jail... because they are guilty of a more serious crime than apology. They are members of the Sendero Luminoso.”
In addition to their calls for a pay rise, the teachers also reject the evaluation system which has been implemented by the Education Ministry this year.
It includes classroom assessments of teachers' relationships with students and teachers who fail the test face dismissal.
The Education Minister has niow agreed to provide teachers who failed the test with training, and to dismiss teachers only after their third failed attempt.
The government claims that any higher pay rise would affect the country's budget. However, Peru invests only 3,8 percent of his domestic gross product in education — less than neighbouring Bolivia, Colombia and Chile.