Joseph J. Tribble, assistant energy secretary for conservation, announced his resignation yesterday, saying he is weary of Washington and eager to go home to Savannah, Ga.

The resignation, announced at a staff meeting, will be effective Sept. 1 if accepted by President Reagan.

Tribble, a longtime Republican loyalist who has headed the Energy Department's Conservation Division since May, 1981, has been under attack for months from consumer groups and members of Congress who have accused him of dismantling the government's conservation programs.

He also drew the wrath of a bipartisan group of lawmakers last October when he fired Dr. Maxine Savitz, DOE's top conservation expert, for refusing to accept a transfer to Colorado. Energy Secretary Donald P. Hodel later backed Tribble's decision.

The resignation, however, comes amid signs that the Reagan administration is softening its approach to energy conservation.

In an annual report to Congress a year ago the department called conservation a voluntary activity in which there was "little need for federal participation," and it has cut budget requests for conservation by nearly 80 percent in the last two years.

But in a final draft of a new National Energy Policy Plan, which was due to be made public last month but has yet to be released, the department reportedly calls conservation "as important as production" in determining the national and world energy situation.

DOE officials said yesterday that Tribble was not asked to leave, and that he had been planning his departure since January.

"He just said he was 63 years old, tired and eager to rejoin his family in Georgia," a DOE spokesman reported.

Tribble, who came to the government from the Union Camp Corp., a paper-products firm, reportedly has no immediate plans for future employment.