President Reagan, who often jokes about moving the seat of government to California, will take a temporary step in that direction next week when he convenes meetings of his top national security and economic advisers in Los Angeles.

After 10 days at his ranch, Reagan will spend Monday and Tuesday in meetings about what have become the most urgent issues confronting the administration -- how to base the MX missile, what kind of bomber to build and what budget cuts to make in the next three years to balance the budget in 1984.

Secretary of State Alexander M. Haig Jr., Defense Secretary Caspar W. Weinberger, national security adviser Richard V. Allen and Reagan's trio of top aides, Edwin Meese III, James A. Baker III and Michael K. Deaver, will meet Monday at the Century Plaza Hotel with other aides on defense questions.

Until a few days ago, presidential aides had been saying they hoped to reach a final decision next week on the MX and on whether to build the B1 bomber.

With the Air Force opposing a plan to place the missiles in specially outfitted airplanes, the decision timetable apparently has slipped. Reagan told reporters Thursday that no decision would be made until after he returns east Sept. 3.

After Monday's national security meeting, the president will meet with Charles Z. Wick, director of the International Communication Agency. Wick, a longtime friend of the Reagans, has not seen the president since Reagan nominated him, deputy press secretary Larry Speakes said.

Reagan will attend a Republican fund-raising party in the evening before turning his attention Tuesday to budget questions in meetings with Office of Management and Budget Director David A. Stockman, Treasury Secretary Donald T. Regan, Murray L. Weidenbaum, the head of the Council of Economic Advisers, and other aides.

Large budget cuts for the next three years must be identified if the president is to attain his often-proclaimed goal of a balanced budget in 1984.

Reagan has promised to decide next week whether to resume sending U.S. warplanes to Israel. Shipments were suspended after Israeli planes destroyed a nuclear plant in Iraq June 7.

On Thursday, Reagan plans to visit the nuclear aircraft carrier Constellation as it steams about 65 miles off the California coast, where he will watch training exercises.

The president will meet with a group of corporation and foundation executives from around the country Friday to discuss revitalizing private support for the arts and humanities. Reagan wants to encourage private contributions to make up for federal support he has eliminated.