In an interview with the Sunday Independent he lashed out at the union, which this week called for Basic Education Minister Angie Motshekga to resign.
He wished Sadtu could "one day appreciate the importance of them articulating fundamental issues … that project them as willing to improve the education of our children, particularly the education of a black child".
According to the report, Motshekga has angered Sadtu by withdrawing an accord protecting collective bargaining.
Mantashe said Sadtu general secretary Mugwena Maluleke appeared angry.
"To me a leader who is angry doesn't appreciate that there are many followers who are angrier than him.
"And you can even stand up, and accuse them of sabotaging education … because they have not appreciated the importance of education."
Maluleke told the newspaper that Mantashe, Motshekga and basic education department director-general Bobby Soobrayan were not acting in the interests of education. – Sapa