Rabbi Baruch Korff has resigned as head of the President Nixon Justice Fund and been succeeded by Lloyd R. Johnson, an Ann Arbor, Mich., nursing home operator and longtime supporter of the former chief executive.

In a letter to 4,000 contributors to the Washington-based fund, which has reported raising $350,000 to help pay Nixon's legal bills, Johnson said the fund will not make public appeals for donations.

"I recently visited with President Nixon and he is of the same mind as I am, i.e. not to conduct public appeals but to leave it entirely to the discretion of his friends and supporters," Johnson said. "Friends of the President do not have to be urged to contribute," he said.

For the present, Johnson said, the fund will concentrate on the case now before the Supreme Court under which Nixon's lawyers are seeking reversal of an appellate court decision to release 30 White House tape recordings played during the Watergate cover-up trial of top Nixon advisers. "This is a cardinal issue and will affect the presidency for generations to come," Johnson said.

Koff, one of the former President's most ardent defenders during House impeachment hearings and the founder of the Nixon legal defense fund, said the fund is now an "ongoing matter" and it was time to step down.

He said he will continue to be active in the United States Citizens' Congress, formerly the National Citizens' Committee for Fairness to the Presidency, and said his resignation "does not diminish my support for President Nixon in any way."