A parent at Batley Grammar School in West Yorkshire says the cartoon was taken from Charlie Hebdo, the French satirical magazine that was attacked in 2015 by Islamic terrorists who killed 12 people.
The cartoon was shown to students during a religious studies lesson on March 22, according to a letter to parents seen by Sky News.
School leaders were forced to apologize, admitting that it was “completely inappropriate” and “had the capacity to cause great offense”.
Depictions of the Prophet Muhammad are considered deeply offensive in Islam.
On Thursday, people gathered outside the school to demand the resignation of the teacher involved.
Video footage posted to social media shows men wearing masks crowding around the school door.
A policeman is seen reading a statement from the school as protesters shout that they want the staff member “sacked”.
The letter seen by Sky News reads: “The school would like to thank the parents who contacted us on Monday March 22 raising their concerns about a resource used in an RS lesson that day.
“Upon investigation, it was clear that the resource used in the lesson was completely inappropriate and had the capacity to cause great offense to members of our school community, for which we would like to sincerely and fully apologize. ”
He goes on to say that the image has been removed from the teaching materials and all religious studies content will now be considered in light of the complaint.
Yunus Lunat, an executive member of the Indian Muslim Welfare Society in Batley, told Sky News he believed the teacher “ran out of script” and was trying to “provoke”.
“They talk about free speech, but I wonder what free speech has to do with a RE lesson. ”
“You will never see a picture of the Prophet Muhammad in our mosque, in any mosque in the world. This is not acceptable, ”he added.
“It gives you some idea of why these cartoons are causing aggravation. ”
Mr Lunat said he was also concerned that the debate could be “hijacked” by people not directly related to the school.
West Yorkshire Police said in a statement: ‘We are aware of a small protest at the school, which is still ongoing. Local agents of the district are present »
Sky News has contacted the school for further comment.