More than 1,200 area clergy received letters this week from the Interfaith Conference asking them to help their communities both cope with and protest the estimated $100 million in local budget cuts planned for next year by the Reagan administration.

Clergy were asked to step up community programs for the poor while helping those affected by the cuts to start letter-writing campaigns and request public hearings. They also were asked to preach on the issue.

The conference, representing local Protestants, Catholics, Jews and Moslems working cooperatively to solve community issues, said the $100 million in estimated cuts for the metropolitan area was calculated by local governments.

"There are a number of persons on the Hill who are making statements that the religious community can take care of these people" affected by the cuts, said the Rev. Clark Lobenstine, director of the conference.

"We're saying no, it's the government's job to give services to the people in this country. Religious institutions will be filling a lot of gaps, but not huge holes. There's no way in this world that we can come up with $100 million.

"Churches are already doing a great deal for the needy," said Lobenstine, "but requests [for assistance] at many churches are increasing" at a time when economic conditions will prohibit parishioners from donating increased sums.

Lobenstine suggested that protests and "continued vigilance" may help restore some of the funds.