The situation escalated and one pupil threatened to forcibly remove the hijab of one of the Muslim pupils and film it.
One of the Muslim pupils tried to push the phone aside and the attack turned physical, he said.
A video of the incident emerged and ended up being shared on social media and between pupils.
One of the Muslim pupils had to be taken to hospital for a check-up after suffering blows to the head.
Rizwan said during the course of the attack one girl's hijab was forcibly removed.
Her friends quickly tried to cover her head.
The attack was a "serious disrespect to our religion and community", he said.
The account was backed up by a family member of one of the pupils.
She said the attack on the pupils was not only bullying, but was a "hate crime".
The school needed to take responsibility for addressing racially charged verbal and physical abuse, the family member said.
Rizwan said the Muslim community was "hurting". "We are frustrated and angry.
"Schools should be a safe space for pupils and the offenders need to face consequences."
The Otago Muslim Association was meeting the school.
The pupils had returned to school and their teachers were trying their best to ensure they felt comfortable, he said.
Otago Girls' High School principal Bridget Davidson declined to answer any further questions about the incident, including the accusation it was racially motivated.
"Out of respect for each of the young people involved, it is not appropriate to comment further on the details," she said.
