"There is a crisis in education, but it is the root problems that need to be corrected and solved," Naptosa's president Esrah Ramashela said in a statement.
"Declaring teaching an essential service is not going to make dysfunctional schools and incompetent teachers any more functional or competent."
He was reacting to the Democratic Alliance's call for teaching to be declared an essential service, which meant teachers would be barred from striking.
Ramashela said this was "concerning and surprising".
In a statement on Monday, DA spokesperson James Lorimer said the party submitted the application to the essential services committee, which falls under the Commission for Conciliation, Mediation and Arbitration.
The DA contests that, given the crisis the education system is in, and the significant inconvenience that this causes for children, teaching should be declared an essential service until the system improves.
"South African children receive one of the worst standards of education in the world, a fact confirmed by a variety of studies," Lorimer said.
"There are many reasons for this, but it is certain that nothing can be done to improve the situation without first having all teachers in their classrooms for all the hours that their contracts require them to be there."
While Ramashela acknowledged there was a crisis needing to be addressed urgently, he maintained this was "not the way to go".
There were too many critical issues that would go unresolved if the DA's application were to be approved.
These include the supply of new teachers, the number of unqualified teachers, the use of teachers outside their areas of specialisation, lack of infrastructure and resources.
"We cannot afford to risk directing attention away from the real issues," he said.