Colin Lowther, head of Southfield primary in Ealing, was told by school governors last week to reinstate the five to nine-year-old children as soon as possible.
He banned them after the mother of four Traveller pupils, her teenage daughter and a daughter from the other family, allegedly attacked a Somali mother in the playground last month, breaking her finger. A parent governor who tried to intervene in the incident was also attacked.
As The TES went to press, the children were still not in the school.
Mr Lowther is supported by the National Association of Head Teachers, and the union and parents this week accused Ealing council of leaving him in the lurch.
David Hart, NAHT general secretary, said Mr Lowther would comply with the demand to reinstate the pupils despite concern about the risk of further violence.
He said Ealing had failed to use its legal powers to protect employees from violent intruders because it did not take out an injunction or conduct a risk assessment on health and safety grounds.
Ealing council has now promised to launch a review to see if legal guidelines were followed. It has maintained throughout that excluding the six children for their relatives' behaviour was unlawful.
Security has been tightened at the school where there are now locked gates, security cameras and an intercom. But a parent, who did not wish to be named, said the measures would do nothing to stop a repeat of the attack.
She said returning the Traveller pupils to the school would make other parents remove their children. "Ministers can't talk about zero tolerance of violence in schools unless it applies to everybody," she said.
At a noisy meeting of parents and governors on Tuesday night, governors suggested the children might be bussed to Southfield to avoid further confrontations.
The demand to reintegrate the children was supported by only four governors, with two votes against and six abstentions. Four parent governors resigned in protest after the decision.
Before the vote, Colin Bastin, the LEA-appointed chair of governors, warned governors would face claims of discrimination if they refused to readmit the pupils.