A teacher has been censured after he punched a boy who taunted him by saying he had a "moustache like a paedophile".

The male teacher punched a 13-year-old student in February 2018 after a touch rugby game, a Teachers' Disciplinary Tribunal decision, released on Tuesday, said.

As the teacher came off the field, the student made a comment about the teacher having a "moustache like a paedophile would".

The teacher then approached the student and asked he wanted a smack in the face, before punching him once on his right cheek, the decision said.

The tribunal granted name suppression for the teacher, the student and the college.

According to the summary of facts, the teacher initially walked away before returning and saying: "You're not laughing now".

The student said he thought the teacher was joking. He experienced some redness and soreness to his right cheek.

Before the incident, the teacher had been "play-fighting" with the student and kicked his bottom, the tribunal said.

Shortly after the incident, the teacher admitted he had hit the student.

He was charged with assault however was granted a discharge without conviction. 

Immediately after the incident, the teacher wrote to the student taking responsibility and expressing his regret, the decision said.

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"He was not able to present the letter or express his regret directly to the student, as he was told to stay away from the school; and the student did not take part in the restorative process.

"As part of the diversion contract plan he made a donation of $500 to charities and provided evidence of counselling sessions aimed at assisting him to cope with legal proceedings and assisting him to recognise and more helpfully respond to painful emotions including depression, anxiety and anger," the summary of facts said.

The teacher said he was frustrated the student had continued to "give him cheek about his moustache" and it upset him, as a male teacher, to be called a paedophile. 

The student had previously made a comment about the teacher's moustache, the decision said.

The teacher is receiving ongoing counselling and medication for depression and anxiety.

He said when he punched the student it was a "paradoxical reaction" after being prescribed Lorazepam, a medication he was prescribed for stress.  He ceased using Lorazepam once he realised its possible effects on him. 

The tribunal found the teacher's actions amounted to "serious misconduct".

"Punching a child's head is a very serious matter. We recognise that the respondent was offended by the student's jibes about his moustache, but just as a student cannot retaliate towards another student in this manner, neither can a teacher."

"The respondent's behaviour was totally unacceptable and set a very poor example to the student, not to mention that it could have had some very serious physical consequences for the boy."

However, the tribunal was satisfied the teacher had taken appropriate steps following the assault.

He was censured and ordered to disclose the tribunal's decision to any future employer in the next two years. He must also be mentored by an approved colleague for a year.

The teacher was also ordered to pay $3397.52.