“We have observed racist undertones underpinning these unfortunate and unjustifiable disruptions,” provincial secretary Tseliso Ledimo said in a statement.
“It is the responsibility of all of us to eliminate the demon of racism wherever it rears its ugly head.”
Earlier on Friday, public order police had to form a buffer between two groups of protesting parents at Roodepoort Primary School.
A group of coloured parents started protesting at the school earlier this week, demanding a coloured principal. They claimed the process of appointing black principal Nomathemba Molefe was flawed.
Children were prevented from entering the premises and schooling ground to a halt.
Gauteng education department spokeswoman Phumla Sekhonyane said the department investigated the community’s claims last year.
“[Investigators] found that there was no evidence of the alleged irregularities in the process of appointing the current principal,” she said.
Ledimo said Sadtu was disturbed by the disruption of teaching and learning at the school.
Read more: Police monitor school in Roodepoort
“This is orchestrated by some parents and teachers who have allegations of maladministration against the school principal,” he said.
“All these allegations, including recruitment procedures followed in the appointment of the principal and the deputy principal were subjected to an independent forensic audit investigation.”
The report cleared the principal and also indicated that the process followed in appointing the principal and deputy principal complied with the relevant policies and legislation, he said.
“It is therefore our firm view that the disruptions are not related to the unfounded allegations.”
The union condemned the “backward behaviour” in the strongest possible terms and called on all stakeholders to restore teaching and learning at the school.
On Thursday, Gauteng education MEC Panyaza Lesufi called an emergency meeting with community members.
“At this meeting it was decided that we should act in the best interests of the children.”
Molefe was temporarily removed from the school while the department negotiated with parents.
The Star reported on Friday that police had to escort Molefe from the school while parents banged on her car and poured water on it.
They reportedly held placards and chanted, “die hoof moet uit [the principal must go]”.