Cuban Foreign Minister Isidoro Malmierca arrived here today in one of the first sustained efforts to achieve a negotiated settlement in the two-month-old war between Iran and Iraq.

The Cuban envoy came to the Iraqi capital immediately following a round of talks in Tehran with members of the Iranian Supreme Defense Council, the highest governing body of the country for the duration of the war.

The council asked the Cuban envoy for specific clarifications of his peace proposals, an act that has prompted speculation here that Iran may be softening its positions somewhat in view of economic difficulties caused by the war.

Although all previous mediation efforts by Malmierca, the 40-nation Islamic Conference and the nonaligned diplomats at the United Nations have foundered on the intransigence of both sides, Third World diplomats here have been encouraged by the fact that while in Tehran, Malmierca was not summarily dismissed or given the usual litany of complaints about Iraq's "agression."

The request for clarification of Malmierca's peace proposals was publicly acknowledged two days ago by Hojatoleslam Mohammed Ali Khamenei, a leading member of the Supreme Defense Council. In meetings with several nonaligned ambassadors here today, Malmierca hinted privately that he would be relaying questions for clarification from Tehran to Iraqi President Saddam Hussein, whom he will meet Friday.

While Malmierca has not divulged the details of his proposals, they are generally believed to follow the lines advanced by the nonaligned group at the United Nations late last month, which called for a simultaneous recognition by Tehran of Iraq's sovereignty over the disputed Shatt-al-Arab waterway in return for Badhdad's immediate withdrawal of its troops in Iran's oil-rich Khuzestan Province.

Malmierca, who was making his third visit here since the war began in September, was acting at the request of Cuban President Fidel Castro, the leader of the nonaligned nations movement. Malmierca's visit began just days before the arrival of Sweden's Olof Palme, appointed earlier this week by U.N. Secretary General Kurt Waldheim to sound out Iraq and Iran about ways in which the hostilities between them could be brought to a quick halt.

Signifcantly, as Malmierca arrived here today, President Hussein was privately addressing a group of about 500 top bureaucrats to restate his government's position that he would proclaim a cease-fire and withdraw his troops immediately once Iran recognizes Iraq's "legitimate rights."

Earlier this week, Saddam Hussein reiterated at a press conference that these legitimate rights included acceptance of Iraqi sovereignty over the Shatt-al-Arab and certain minor territorial adjustments along the length of the border that separates the two warring OPEC nations.

Although he did not specifically tie it to the issue of a peace settlement, President Hussein also revived the question of the tiny islands of Abu Musa and the Greater and Lesser Tumbs near the mouth of the Persian Gulf. The three islands were taken by force by the late shah of Iran in 1971 from the tiny Arab gulf sheikdoms of Ras al-Khaimah and Sharjah.

Saddam Hussein's renewal of demands that the islands be returned to the sheikdoms, now members of the United Arab Emirates, was viewed as a way of restating his claim that his war was not just a war between two neighboring nations, but a war of the Arab nation as a whole against their historical antagonist from Persia, now modern Iran.