The White House regards President Carter's speech at the U.S. Naval Academy tomorrow as an opportunity to clarify the status of U.S. Soviet relations after weeks of mounting tensions between the two superpowers. Carter already has spent many hours working on the speech, having met for two hours Sunday with his principal foreign policy advisers, Secretary of State Cyrus R. Vance and national security affairs adviser Zbigniew Brzezinski.

The speech, at the academy's commencement exercises, will come in the context of increasingly sharp administration attacks on Soviet and Cuban activities in Africa and reports that U.S.-Soviet relations are at such a low point that the prospects for a new strategic arms limitation talks (SALT) agreement are in danger.

Carter hopes to use the speech to reduce the conflicting domestic political pressures on the White House that have built up over the issues, according to White House officials.

"We've got the liberals thinking we're ready to jump into a war in Africa and the hawks thinking we're about to give away the store and sign a disadvantageous treaty with the Soviets," one senior presidential adviser said. "It's time for the president to step forward and say where we stand."

In the view of White House aides, the public wants a new SALT accord to end the arms race and for the administration to be tough in dealing with the Russians. Given greater American Soviet tension, one aide said, there is a danger that public opinion will begin to solidify around the idea that a halt to the SALT negotiations would somehow "punish" the Soviets.

The United States needs a new arms agreement at least as much as the Soviet Union, this official said.

Noting that the Soviets spend about 13 percent of their budget on the millitary, he added."There is no evidence that our country is willing to invest that kind of money over the next 10 to 15 years to keep up" should a new round in the arm race follow a SALT breakdown.

Officials acknowledge that there has been "some uneasiness" both at home and among American allies about America's strength and the president's willingness to use it to counter what they called "greater Soviet agressiveness" in Africa.

This comes after a series of Carter decisions - the scrapping of the B1 bomber, the moratorium on development of an enhanced radiation (neutron) weapon and the return of the Panama Canal, which, officials said, "while correct individually, can be portrayed as 'giving the store away.'"

Carter hopes, they said, in the Annapolis speech to balance his expressed concern about Soviet actions with a reassertion of the basic military and economic strength of the United States.

To that end, they said, he may contrast the security the United States enjoys in the Western Hemisphere with the situation of the Soviet Union, which keeps a million men under arms on its border with China and other large armies in Eastern Europe.

But in relation to Africa, these officials said, Carter realize there is "not much tolerance" among the American people for a major U.S. role, even to counter Soviet influence.

Thus, he is likely to balance his criticism of Russian-Cuban intervention with reassurance that the United States is not about to embark on a unilateral military effort in Africa.

Carter appears to be more personally involved in writing the Naval Academy speech than is generally the case, another sign of the importance he attaches to it. Officials said the speech is difficult to write because it will be aimed at more than one audience - American public opinion, Soviet officials and those officials within the administration who are concerned about the direction of American Soviet relations.

The speech, while reaffirming the basic thrust of U.S. policy toward the Soviet Union and the president's commitment to the SALT negotiations, will also deal with "the changing circumstances of the last three or four months," one aide said. Those circumstances, chiefly the stepped up Soviet and Cuban activity in Africa, have resulted in "some necessary adjustments" in U.S. policy that Carter will both explain and defend, he said.

Another official said the White House hopes the speech is not interpreted as signaling a fundamental shift in U.S. policy or is seen in personal terms as a "victory" for either Vance or Brzezinski, who have been cast in the roles of dove and hawk respectively in this administration.