The Board of Deputies says it would be concerned if the Conservatives went ahead with a proposal to limit child benefit for families with more than three children.
Dominic Raab, Tory MP for Esher and Walton, told BBC Two's Newsnight that the party was considering capping the benefit.
A Board spokesman responded this week by saying the organisation would be "concerned about the effect any measures like these would have on families in our community".
Reducing child benefit would particularly hit the Charedi community, where many families have six or more children.
The Board, in its Jewish Manifesto published for the general election, has called for recognising "the needs of larger families whose religious and cultural needs make them less adaptable to welfare reforms".
Community representatives should be consulted on the potential impact of benefit changes, according to the manifesto.
Ukip is currently the only party committed to such a policy, proposing to limit the benefit to just two children.
Parents currently receive £20.50 a week for their first child and £13.55 for every other child they have.
Mr Raab said the welfare system should send a message "about personal responsibility and that includes parents saving and taking some responsibility for the size of their family".
Chaya Spitz, chief executive of the Interlink Foundation which advises Charedi charities, said capping the benefit would reflect an "anti-family mindset" and tell parents with more than three children "you are on your own". She said the change would also affect middle-income families.
Criticism of the proposal also came from Liberal Judaism chief executive Rabbi Danny Rich.
He said: "Most of us cannot really afford the children we have. The child benefit system is a modest way for society to reflect that it values children."
But Harvey Odze, a strictly Orthodox councillor in Hackney, the borough with the country's largest Charedi community, said that he had not given the proposal much thought "because I don't think it's going to happen".
