The chair of governors of JFS has accused some parents of running to the press to make “wild and inaccurate accusations and complaints” about the school.
In an email sent to families with children at the school, Steven Woolf also criticised the “pack mentality” of parents who posted “hysterical” messages about JFS on social media.
Mr Woolf said he was expressing “the collective disappointment of the entire governing body at the sort of behaviour”.
His remarks came after the JC reported the mugging of a 16-year-old boy which had taken place close to the school , in Kenton, north-west London.
The child’s mother, Nicki Hari, had contacted the newspaper to raise concerns about the school’s security.
Earlier in the week, the JC had also reported that the school’s website was targeted by hackers.
Mr Woolf told parents that the school, which has over 2,000 pupils and is the largest Jewish school in Europe, took the matter of the mugging seriously and was investigating the incident.
He said: “However, not satisfied that the school would deal with this appropriately, the parent chose to contact the press.”
He added: “The inordinate amount of time taken up by the school in dealing with the direct and indirect involvement of the press results in less time for the school to concentrate on the education, development and welfare of our children… Whatever the specific details of this incident, what is clear is that the school should be left unobstructed to do its job”.
He also claimed that JFS staff had been “hounded” by the press.
Referring to parents’ use of social media, he wrote: “We have received complaints from some parents troubled by the hysterical nature of some other parents on social media and the ‘pack mentality’ that some choose as an appropriate avenue of complaint.
“What sort of lesson are we teaching our children if we behave in this way?”
In a separate email to parents, JFS headteacher Jonathan Miller accused a section of “our parental body” of “inappropriate fearmongering” after the mugging, which had led “to some of our younger students feeling unsettled about their journey to school this morning and is both irresponsible and unfair to our students”.
He said the school switchboard had been jammed with calls from parents concerned about “rumours” surrounding the incident. In one case a receptionist had been abused by a caller.
Mr Miller wrote that muggings were a "fact of life" for pupils across London.
"Please be reassured that we continue to have a high security presence outside the school, including between Kingsbury station and the school gates. However, this cannot be guaranteed to prevent all crime and to expect otherwise is both unrealistic and misguided."
Meanwhile, the mother of the mugging victim has set up an online petition appealing to Mr Miller to increase security at the school.
Ms Hari wrote: “After my son was mugged by the entrance of the school gates of JFS on November 11 2015, we need to ensure the safety of our children when entering and leaving the school.
“This means that, until the last student has left the site, there needs to be enough security on the parameters at all times.”
More than 110 people have signed the petition.