Education Minister Caitríona Ruane has called for action to end the dispute at Movilla High School.
The school has been closed to pupils until further notice due to an ongoing strike by some teachers.
NAS/UWT members are protesting over having pay docked because they refused to teach a pupil who they say assaulted a teacher at the Newtownards school.
However, the South Eastern Education Board supported the school's governors decision not to expel the child.
Speaking in the assembly on Tuesday Ms Ruane said that negotiation was the only way forward.
"We need to see this issue resolved. Whether it be by the offer of the children's commissioner to mediate, the auspices of the Labour Relations Agency, or local dialogue," she said.
"I would also ask that the privacy of the pupil and their family be respected by all involved."
Strikers have said their morale is high and that they have received plenty of support.
"We've have a very good response from the general public and other teachers generally," said the union's Fred Brown.
Another union, the Association of Teachers and Lecturers has balloted its 10 members about refusing to teach the pupil in question.
In a statement, the SEELB described the incident as having been "appropriately and proportionately dealt with" by the board of governors.
About 540 pupils at the school in Newtownards arrived for class on Monday, but were sent home.
The board had told the protesting teachers they would not be paid, even if they were teaching other classes normally.
The restoration of that pay is now the only barrier to talks at the Labour Relations Agency.
The union wants guarantees the pay will be restored, the board wants no pre-conditions. The union has described this approach as "confrontational".
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