A U.S. delegation flew to Saudi Arabia yesterday to discuss letting American forces use Saudi bases in times of crisis.

Carter administration officials, in confirming the trip last night, said the delegation was not seeking a launching pad for military action against Iran.

Instead, they stressed, the objective is to get permission to use Saudi bases for U.S. planes and troops if another crisis erupts in the Middle East.

The upcoming formal discussions with Saudi Arabia underscore President Carter's intention to prepare the United States for a more activist role in Third World struggles, especially in the oil-rich Persian Gulf area.

The president signaled his intent in his defense speech last week in talking about organizing a Rapid Deployment Force to rush to distant conflicts before they get out of hand.

"We must understand that not every instance of the firm application of power is a potential Vietnam," Center said last week in a portion of his defense speech highlighted by a White House official who briefed reporters.

Administration officials said the discussions about using Saudi bases are part of the planning for the Rapid Deployment Force.

The Iranian crisis gave new urgency to Pentagon efforts to find temporary launching pads for American military power in far-off trouble spots, officials said. The aricraft carrier Kitty Hawk, they pointed out, took more than a week to sail from the Pacific to the Arabian Sea to put more fighter-bombers in range of Iran.

Besides talking with the Saudis this week, Pentagon officials are studying other countries -- including Egypt, Is rael and Morocco -- with an eye to asking for rights to use bases there in an emergency.

The U.S. delegation to Saudi Arabia is headed by Robert J. Murray, a deputy assistant secretary at the Pentagon for Near Eastern affairs. He has been serving on the administration's Iranian task force as a representative of the Pentagon's "little State Department" -- the International Security Affairs office.

The Pentagon delegation is expected to remain in Saudi Arabia most of this week. No State Department officials went along, indicating an exploratory mission rather than one to make formal agreements on the use of Saudi bases.

The U.S. Army Corps of Engineers is supervising the construction of billions of dollars worth of military facilities in Saudi Arabia that could be used by the American military temporarily if formal use agreements are reached with the Saudis.

Administration officials said that the type of basing the president has in mind was outlined Sunday by Defense Secretary Harold Brown on "Face the Nation" (CBS, WDVM).

"We naturally have to rethink the nature of our presence in that general area," said Brown in discussing the turbulence in Iran and Afghanistan. The administration "will be talking with various countries in the area about how we might increase our presence.

"I don't believe that American bases as such in that area are the right way to go. A number of those countries in the area can maintain bases which, in an emergency in which they asked our help, we could then come in and use. Nor do I see formal alliances."

The United States, starting with the fiscal 1981 defense budget going to Congress next month, is expected to spend billions to build huge planes to carry arms and Rapid Deployment Force troops to distant points such as the Persian Gulf. Saudi Arabia has bases that could accomodate such aircraft.

Some Pentagon officials oppose the idea of U.S. forces using Saudi bases, even on a temporary basis, on the ground that such a highly visible American presence would provoke Arab protests and hazard the existing Saudi government. The Saudis have been cool to the idea in the past.

At the same time the Murray delegation is meeting with the Saudis, Pentagon specialists will continue their studies of airfields and ports in other Middle East nations where the Rapid Deployment Force could land. The first three Marine brigades to spearhead that force are expected to be ready by 1983.