Caught in a financial squeeze, Iran has abandoned its ambitious dream of having about 20 large nuclear power plants in operation by 1994 and has notified West Germany that it will not decide for another year whether to go through with the $8 billion purchase of its next four reactors, a top government official said yesterday.

The new president of the Atomic Energy Organization, Ahmad Sotoodehnia, said in an interview that the future of Iran's nuclear energy program will depend on an inter-governmental reevaluation of the country's "total national energy policy."

While emphasizing that work on the first four nuclear power plants already under construction will continue, Stoodehnia said: "There's definitely a slowdown in the program at this stage of the game, and an awful lot of rethinking of the Iranian energy program."

Shah Mohammad Reza Pahlavl's nuclear goal - which experts feel might well have cost Iran $50 billion over the next two decades - thus appears to be suffering the fate of the vast military purchases being cut back to channel money into programs aimed at putting a damper on growing social unrest. In addition to the temporary freeze on power plants, Sotoodehnia said the slowdown in the Iranian nuclear program will be felt in manpower training, research and other areas.

The new Isfahan Technological Center, which was to be the backbone of Iran's nuclear power plant and fuel program, had been scheduled to begin partial operation by 1981.

"As a result of the economic crunch on the country, there's not enough money for it," Sotoodehnia said. "It will be built, but not at the fast rate that was planned."

Beyond causing dismay in West Germany, which is building Iran's first two nuclear power plants near the Persian Gulf port of Bushehr, the Iranian moratorium on new contracts is certain to create gloom in France and the United States as well.

The French firm Framatome, which is just starting construction of Iran's third and fourth reactors on the Karun River, expected to get the contract for at least two additional power plants under a basic accord that France signed with Iran last June. That contract has now been postopend indefinitely.

Even more remote are the hopes of U.S. firms like Westinghouse, which had been expecting under an Iranian-American trade accord signed in 1975 to ultimately get contracts for eight reactors. This could have brought American companies as much as $20 billion.

Those contracts were blocked pending completion of a nuclear cooperation agreement between the United States and Iran, which both countries finally initialed in August. Now, Sotoodehnia said, the prospect for those sales have faded.

"There is no immediate plan to know exactly what the future would be, he said. The future of the four [under construction] is definitely known, and the next four are postponed, and the future of the whole program depends on the revaluation of the total energy scheme of the country."

Nobody in Iran could have been more unhappy over the slowdown in the nuclear program than Sotoodehnia, who took over as head of the Atomic Energy Organization less than a month ago when Akhar Etemad, its founder, was relieved of the post following allegations of mismanagement and embezzlement.

When Sotoodehia was presented to the shah as the new atomic energy chief, the shah reported told him to speed up the pace of Iran's nuclear power program - and ordered establishment of more atomic reactors at different parts of the country.

The subsequent decision to hold up the nuclear program, in Sotoodehnia's view, reflects the Iran's atomic energy plants - with their large capital costs - are a high visibility target at a time of mounting social and economic unrest.

"The capital intensiveness of the program has made lots of difficulties." Sotoodehnia said. "Because we have pulled a lot of capital from the government - this was a top priority program - the other sectors weren't at ease to see that this project gets so much capital and so much free hand. All these things have created an atmosphere of unrest."

The Iranian opposition, right and left, also has campaigned against nuclear energy, arguing that Iran could build a power program around its vast natural gas reserves for about one-tenth the cost.

These arguments clearly distress Sotoodehnia, for he concedes that strictly from an energy standpoint, Iran probably could get by on natural gas for possibly as long as 100 years.

"We do have enough fossil fuel at the present," he said.

He added that one possible result of the reevaluation "is a short-term plan - which definitely is a very short-term solution - to drill more gas wells on the new reservoirs, and get the gas piped, and start to install thermal power stations" in place of planned nuclear plants.

But, contended Sotoodehnia, Iran "should have a program of nuclear energy not only for supplying energy from this source, but a acquire technology - to acquire the know-how.

"They say our present nuclear program is expensive," he noted. "Why? Because we are paying the price for not acquiring this technology over the past 20 years."

Sotoodehnia conceded that the timetable for the original program might have been too ambitious.

"Just from the transfer of technology and manpower training, we could not match the rate we were going," he said. "So this, by itself, may need a somehow different approach to the problem."

The big question at this point is whether the new approach will be to end the program with the four plants under construction.

"Maybe the result of the study will be that the program should proceed with a few years' delay," Sotoodehnia suggested, hopefully.