SANTA BARBARA, Calif.--President Reagan has invited the leadership of Nicaragua's Contra rebels to Los Angeles to give "his personal assurances" of commitment to their cause, the White House said yesterday.

Spokesman Marlin Fitzwater, confirming a disclosure Wednesday by Contra official Alfredo Cesar, said Reagan will meet with the entire six-member directorate of the Nicaraguan opposition on Aug. 27.

Fitzwater, briefing reporters as Reagan vacationed at his nearby mountaintop ranch, said the meeting was arranged in part, but not solely, because of the Contras' complaints that they had been poorly consulted by the White House in connection with recent Central American peace initiatives.

He said there was some urgency to the session, which likely will be held in Reagan's hotel suite in Los Angeles, because "a lot of things have happened in the last two weeks."

Contra figures have voiced concern about the administration's commitment to their cause and about statements by the administration that have sent conflicting signals about its intentions.

"Make no mistake. We want to demonstrate to conservative leaders, to the [Contra] directorate, to the nation, our commitment," Fitzwater said.

Asked whether the U.S. government would be paying for the flights of the Contra directors from Washington to Los Angeles, the spokesman said he didn't know how they were getting to Los Angeles, "but I hope we're paying for it."

Fitzwater also said he saw nothing improper in Reagan holding a high-profile, although private, meeting with Contra leaders. The peace plan submitted jointly by Reagan and House Speaker Jim Wright (D-Texas) contemplated a low administration profile on the question of seeking further military assistance for the rebels.

The Reagan-Wright plan set a Sept. 30 deadline, the end of the current budget year, for the leftist Sandinista regime in Managua to demonstrate a willingness to institute the kinds of reforms that could lead to a cease-fire.

But Reagan himself, and several of his top aides, has said that the administration will not desert the Contras, and the president indicated in his weekly radio address last Saturday that support for the Contras must continue until a peace plan and democratization have been implemented.

"I would say that they're going there to discuss the status of the peace plans," Fitzwater said of the Contra directors. He was referring to the Reagan-Wright plan and to a rival plan, signed by the leaders of five Central American nations including Nicaragua, which envisions a Nov. 7 deadline for the kind of change that could lead to a cessation of hostilities in Nicaragua.