The manch believes celebrating Christmas is a step towards forced conversions.
The Hindu Jagran Manch has warned schools in Aligarh not to celebrate Christmas.
The manch says celebrating Christmas is a step towards forced conversions.
News reports Sunday quoted the president of the Hindu Jagran Manch, Sonu Savita, as saying students were being asked to bring toys and gifts to celebrate Christmas.
This he said helped lure the children to Christianity.
The manch's warning is meant for schools at which a majority of the children are Hindu.
Savita said they were also talking to parents' organisations, asking them to refrain from "these activities".
Savita was quoted as saying such activities affect the mentality of Hindu students.
The secretary of the Hindu Jagran Manch, Sanju Bajaj, was quoted as saying that if the schools do not listen, the manch will hold protests outside of them.
The schools meanwhile have said they do not force any child to celebrate a particular festival.
They have also said the manch's demand is unprecedented and "strange".
And that if they do receive the diktat from the manch, they will approach the authorities for help.
The Hindu Jagran Manch is a right-wing Hindutva group affiliated to Uttar Pradesh Chief Minister Yogi Adityanath's Hindu Yuva Vahini,