The Unted States will urge the Soviet Union to play a more constructive role in bringing peace to southern Africa and the Middle East when President Carter meets Soviet leader Leonid Brezhnev at this month's Vienna summit, a senior U.S. official said yesterday.

The official, speaking aboard Secreatry of State Cyrus Vance's plane en route from Madrid to Washington, said the Carter administration plans to press these points with Brezhnev as a reminder that it considers detente "a two-way street." Vance returned yesterday from a two-week trip to Europe and the Middle East.

Specifically, the official said, Carter will seek to persuade the soviets not to block entension of the U.N. force in the Sinai Peninsula and to use its influence to help bring black guerrilla forces into a peaceful solution of Zimbabwe Rhodesia's civil war.

While conceding that "it's very difficult to predict" whether the effort will have any success, the official stressed that these issues are high on the U.S. agenda for the June 15-18 summit.

The main purpose of the Vienna meeting will be to sign the U.S.-Soviet strategic arms limitation treaty. The United States also wants to use the occasion for discussion of a wide range of bilateral and international issues affecting U.S.-Soviet relations.

In the area of bilateral relations, the official said there are reasons to expect "some modest progress" to be made at the summit toward such arms-control goals as limiting weapons sales by the two superpowers. In addition, he said, there is a similar chance of removing some of the barriers to greater trade between the two countries.

He and other U.S. officials on the plane, however, were more pessimistic about the likelihood of the summit porducing any important agreements on those global trouble spots where Washington and Moscow compete for influence.

Some officials said that is especially the case at a time when Brezhnev is ill and major changes are expected in the Soviet leadership. Since these factors have put the Soviet government into something of a stand-pat position, the officials said, Moscow currently is unlikely to make any significant changes in its foreign policy.

Nevertheless, the senior official noted, the situations in southern Africa and the Middle East require that Carter try and convince Brezhnev that a commitment to detente means a more positive Soviet role in the peace efforts underway in these regions.

In the Middle East the United States is eager for the U.N. Security Council to renew the soon-to-expire mandate of the Sinai Force in order that it can continue acting as a buffer between Israeli and Egyptian forces while those two nations work toward implementing their peace treaty.

But the Soviets, siding with Arab states angry at Egypt over its accord with Israel, have hinted strongly that they will use their Security Council veto to block extension of the Sinai mandate. If they do, the United States would be confronted with the difficult task of trying to recruit a multinational force for the Sinai outside of the U.N. framework.

In the case of Zimbabwe Rhodesia, the administration's policy of seeking to promote a peace conference between the new black-led government of Prime Minister Abel Muzorewa and its guerrilla opponents recently has suffered several blows.

Britain's new Conservative government has started to retreat from cooperation with that approach, and Carter has come under pressure from Congress to lift U.S. economic sanctions against Salisbury and recognize the Muzorewa government.

In Vienna, Carter can be expected to urge Brezhnev to refrain from activities that prolong the bloodshed in Zimbabwe Rohodesia - the new name adopted for the country by the Salisbury government. Carter is likely to urge the Soviet leader instead to help prod the guerrillas toward the bargaining table. CAPTION: Picture, A senior U.S. official By Charles Del Vecchio - The Washington Post