U.S. oficials observed yesterday that Iran has not asked for spare parts for its armed forces in return for release of the 52 American hostages, and they said that if it does ask, only nonlethal items will be turned over.

In part this latter assertion is aimed at mollifying Arab governments, which have warned the United States not to make any concession to the Iranians that could exacerbate or possibly lengthen the Iran-Iraq war.

If it turns out that Iran does make the $550 million in U.S. military equipment a condition in the hostage deal, administration officials said, only nonlethal items will be released, seemingly barring shipment of ammunition and guns but not necessarily medical supplies and aircraft parts.

At the Pentagon, officials discouraged the notion that the outcome of the Iran-Iraq war would be significantly influenced by the release of supplies held at McGuire Air Force Base and at Fort Dix, N.J., and mixed in with U.S. equipment at military supply depots around the country.

Iran, they said, has managed to keep limping along in the inconclusive war by dipping into stores piled up by the shah, by fighting its 747 cargo planes into North Korea about 10 times to pick up "hundreds of tons" of antiaircraft guns and small arms in exchange for oil sent out of the Iranian terminal at Lavan on the Persian Gulf, and by sending some of its wounded to Syria for specialized treatment.

However, the airlift of Iranian wounded by C130 transports to Syria was blocked recently by Turkey, Pentagon officials said, which refused to allow the planes to continue flying through its air space.

Although the Pentagon officials refused to list what weaponry and equipment Iran could receive if the $550 million stuck in the pipeline is released, they gave a general rundown of the situation.

When the shah left Iran in January 1979, orders for $12 billion in American arms were in various stages of negotiation. The interim government canceled $8 billion of that $12 billion shortly after the shah's departure to ease financial pressures. The $8 billion in cancellations did not cost Iran anything in penalties because the orders had not advanced to signed contracts.

The $4 billion in orders remaining on the books after those cancellations included such big-ticket items as 160 F16 fighter planes and four Spruance-class destroyers. Fifty-five of the F16 fighters had advanced to signed contracts, meaning Iran would have to pay hefty cancellation costs if another buyer were not found for the planes.

As it turned out, Israel bought the 55 F16s and the United States the four Spruance destroyers. In a move that saved Iran additional cancellation fees, the Navy took Phoenix missiles for the F14 fighter that the shah had ordered.

On Feb. 3, 1979, Pentagon officials continued, the provisional government of Iran -- meaning that under the Ayatollah Ruhollah Khomeini who by then had returned to Iran from exile in Paris -- sent a memo to the Pentagon's arms sales office authorizing it to handle the other orders at issue in "Iran's best interest," to quote a Pentagon official.

The Pentagon disposed of the shah's orders in the subsequent 21 months, except for about $550 million still on the books. If the Carter administration hangs tough on its pledge to release only nonlethal equipment, it would be a final bit of managing of Iran's arsenal by the Pentagon.

Rather than depend on anything still in U.S. warehouses, Iran has been buying weaponry for the war with Iraq from other countries, Pentagon officials said. They said they have evidence of sales by France, but not by Israel. Both Iran and Iraq are negotiating to buy antitank missiles in France, these officials said.

The Pentagon has steadfastly denied that it has taken any action of late to prepare for shipping military equipment to Iran, specifically denying a claim by Sen. Barry Goldwater (R-Ariz.) over the weekend that two Air Force C5 transports were being loaded with spare parts for Iran.