If Iran were attacked by either the United States or the Soviet Union, it would expect the other superpower to come to its aid, Defense Minister Mustafa Ali Chamran said today.

In an interview, he also outlined plans to create a new armed force combining Israeli efficiency and the righteousness of Cromwell's new-model army of 17th century England.

Just as France's geopolitical importance continued to ensure U.S. nuclear protection after the late Gen. Charles de Gaulle withdrew from the NATO military alliance in 1966, so Iran feels that its oil fields and strategic location provide a defense in themselves despite the government's animosity toward the United States.

"We want to have an equilibrium," the American-educated minister said so that "any threat from the United States will face Soviet attack, and vice versa."

"The Iranian government well understands that if there was no American pressure, the Russians would attack Iran, and vice versa," Chamran added in defining Iranian strategy in the wake of the revolutionary authorities' denunciation of the 1959 defense treaty with the United States.

Asked what Iran would do if a Soviet armored column invaded, the 47-year-old civilian defense minister illustrated his point by saying, "We would fight, and at the same time, the United States naturally would come and face the Soviet power."

Outlining Iran's new defense strategy, Chamran said he favored stripping down Iran's half-million strong traditional military establishment to a reservist-based backbone of sophisticated weapons specialists and planners along Israeli Army lines.

They would be supplemented by the Revolutionary Guard corps, now numbering between 20,000 and 30,000 men but expandable, and a basically home-defense army of 20 million adults capable of fighting "peoples' war" against any invader.

Mobilizing and motivating 20 million adult Iranians was first announced when the United States in early December sent a naval task force near Iranian waters following the seizure of the U.S. Embassy here by militant Islamic students. But Chamran specifically mentioned the home-defense concept in discussing threats from both superpowers.

He described an army akin to that promoted by Oliver Cromwell in mid-17th century England. Cromwell's new-model army was guided by puritanical religious fervor and commanded by nonpolitical generals.

Admitting "sensitivity" between the Iranian Army and the Revolutionary Guards, Chamran said that President Abol Hassan Bani-sadr, the armed forces commander in chief, planned to "harmonize" the units over the next year. f

He said "the flow of foreign weapons continues from Iraq, Afghanistan and Pakistan," into Iran, arming dissidents in Kurdistan in the west, the oil province of Khuzestan in the south-west, and Baluchistan in the south-east.

Although opposed to ousted shah Mohammed Reza Pahlavi's fascination with massive amounts of sophisticated military hardware, Chamran said he was "not about to throw away" the inherited arsenal he estimated to cost $60 billion.

American-built helicopters and 190 relatively simple F4s and 166 F5 aircraft were preferred, he said, to the 77 sophisticated F14 Tomcats "which are too difficult" to maintain.

However, he reiterated Iran's earlier refusal to sell either the Tomcats or its nine Boeing 747 military transports.

Iran's 800 or so helicopters were proving "extremely useful to us because of our mountains, bad roads and deserts," he said.

About a quarter of the helicopters and fixed-wing aircrafts was being kept airworthy, he said, with an additional 25 percent held in reserve.

Despite a U.S. embargo in reprisal for the embassy seizure, the minister said Iran was either buying spare parts abroad secretly or making some here.

Asked if spare parts procurement were not proving expensive, he smiled and said, "In any case, they are costing less than during the time of the shah, when there was wholesale bribery and corruption."

Iranian defense policy guidelines favor relying mostly on Western European countries for future arms procurement -- especially Britain, France, Italy and West Germany -- because imperial ambitions were behind them, Chamran said. He said Iran "feared the United States and the Soviet Union."

In the future Iran would not buy what he called "sophisticated aircraft," he said, nor any more of the advanced British-built Chieftain tanks that were being cannibalized for spares. The shah purchased some 875 Chieftains and planned to buy more before the revolutionary authorities canceled that order.

Over the past three or four months, between 7,000 and 8,000 members of the armed forces -- mostly officers among the higher ranks -- have been "retired," Chamran said, adding that the purge was now "almost finished."

Officers purged amounted to 8 percent of the officer corps, he said, explaining that "those who cannot go along with the revolution had better go home."

The 400,000-man armed services and 100,000-man gendarmere were now back to about "75 percent strength," Chamran said. In the initial postrevolutionary months of a year ago, barracks were all but deserted despite repeated calls to report for duty.

Leftists' efforts to impose election of officers have been defeated. But revolutionary fervor, especially among noncommissioned officers, has not diminished, as proved last week when a demonstration by militant Air Force sergeants culminated in the transfer of Maj. Gen. Amir Bahman Bargheri, the Air Force commander. The demonstrators carried copies of a photograph showing Bargheri kissing the hand of the shah's son, crown prince Reza, a common practice under the since-deposed monarch.

Earlier this week, President Bani-Sadr denounced the sergeants. He warned that such demonstrations were "illegal," "counterrevolutionary" and amounted to "rebellion against the orders of the command with the intention of plotting."

Chamran indicated the demonstrations were an unfortunate, if under standable, outgrowth of the anti-shah feeling among radical armed forces members, but did not constitute a sufficient reason to end a workers' council experiment in military ranks.

Chamran, a former researcher at the University of California in Berkeley who claims he stopped working for a U.S. Air Force plasma physics project to protest the Vietnam War, wants to change the basic nature of the Iranian armed forces.

"We want to create a new man," he said, "for a new society."