President Carter, reaffirming his policy of strict U.S. neutrality in the conflict between Iran and Iraq, called the Soviet Union yesterday not to interfere in the escalating fight between the two Persian Gulf neighbors.

"We encourage all other countries, including the Soviet Union, not to interfere in this conflict. The United States itself is following such a policy." Carter said in a statement released while he was campaigning on the West Coast.

The president's comments came amid concern among administration officials that the fighting rapidly is reaching the point where it could frustrate all efforts to unravel the tangled skein of crisis enveloping the turbulent Persian Gulf region.

U.S. officials, speaking privatley, said that if the conflict isn't resolved quickly, it could mean an indefinite new setback for efforts to free the American hostages in Iran, cause major disruptions in the world's oil supplies and put the United States and the Soviet Union in a confrontation even more serious than that caused by the Soviet invasion of Afghanistan.

The officials were quick to stress, though, that where the Soviet Union is concerned they were speaking in relatively long-range terms. As of now, they said, there is no evidence that the Soviet Union, despite its role as Iraq's chief arms supplied, had any role in instigating the conflict or is involved in troop movements or other activities that could affect the situation.

Regarding that aspect of the crisis of most immediate interest to Americans -- the plight of the 52 hostages held by Iran since last Nov. 4 -- U.S. officials said they had no immediate way to assess the seriousness of statements by the Iranian parliament that it will not address the hostage question until the conflict with Iraq is resolved.

In a taped interview broadcast yesterday by a Los Angeles television station, Carter took an almost wistfully hopeful view. "I don't see any way that this altercation between Iran and Iraq will affect the safety or the lives of the hostages, nor the date of their release, but it's too early to assess that with any sort of final conclusion," he said.

However, Secretary of State Edmund S. Muskie, in New York for consultations at the United Nations, sounded more pessimistic. Asked by reporters to freeze further debate on the hostages, Muskie replied: "Well, I think the practical matter is that it probably is frozen while they're involved in the present situation."

In discussing possible approaches the United States could take toward the conflict, administration sources said Washington is severely handicapped by lack of influence with either side.

In addition to the extreme acrimony between Washington and Tehran generated by the hostages crisis, the United States does not have diplomatic relations with Iraq, a radical Arab state that bitterly opposes U.S. policy in the Mideast and that, despite occasional ups and downs in its relations with Moscow, generally tilts toward the Soviet Union in disputes involving the superpowers.

Some U.S. officials are understood to feel the United States should seek some way of siding with Iran. Their reasoning, based on the assumption that Iraq would win an armed conflict, holds that such a result would increase the internal chaos within Iran, strengthen the hand of radical leftist forces there and give Moscow the opportunity to increase its influence over Iran and possible even take territorial inroads there.

But however well-grounded that argument might be in geopolitical terms, it collides head-on with the realities of domestic American politics. Given the massive anti-Iranian feeling in this country as a result of the hostages' plight, there is no chance that Carter would seek to take an openly pro-Iran position in the midst of his tough fight for reelection.

As a result, U.S. sources said, Washington really seems to have no resource other than to cleave strictly to its policy of neutrality in hopes of not antagonizing either side and to watch for opportunities that might provide a way to halt the fighting before it goes beyond the point of no return.

Statements by Carter and other U.S. officials that it would be in Iran's interest to resolve the hostage issue speedily have been interpreted in some quarters as a hint that the United States might repond by relaxing its embargo on badly needed spare parts for Iran's military equipment, largely U.S.-made.

However, State Department spokesman Jack Cannon denied strongly that there is any intention to link release of the hostages to a resumption of arsenal parts shipments. He said the embargo is being "strickly enforced," and, while conceding that Iran might be able to get some parts from other markets, said it would have to pay "a considerable premium."

In addition to taking every opportunity to reassert its neutrality, the main U.S. diplomatic effort at the moment appears to center on what administration sources called "the admittedly slim hope" that the pressure of the international community can be brought to bear on the combatants through the United Nations.

As part of its professions of neutrality, the State Department reaffirmed yesterday that the United States has no plans to fall back on a revived threat to use military force against Iran if the hostage stalemate continues.

Defense Department spokesman Thomas Ross said two U.S. warships are in the Persian Gulf -- the command ship LaSalle, flagship of the Middle East Force, and a frigate -- both approximately 200 miles from the combat area. In addition, Ross added, the United States has 31 ships, 18 of them combat vessels, in the Indian Ocean area, as compared to 29 ships of the Soviet navy.

The State Department revealed that since last Friday the U.S. government has issued three "special warning" radio messages to U.S. merchant vessels in the gulf area. The most recent, issued late Monday night, advised U.S. ships to avoid Iranian waters and the Shatt-al-Arab, the estuary forming part of the Iran-Iraq border.

The department also said that approximately 700 American citizens are believed to be in Iraq, between 200 and 300 of them in the Basra area, which was bombed by Iranian planes yesterday. However, department officials said they had no confirmation of unofficial reports that three or four Americans may have been killed in the attack.