Ayatollah Ruhollah Khomeini and the government of President Abol Hassan Bani-Sadr today turned Washington's declaration of economic and political sanctions against Iran into an opportunity to appeal for public sacrifice to end the economic chaos that has plagued Iran since the February 1979 revolution.

Iranian authorities also took advantage of the heightened crisis with the United States and a brewing armed conflict with neighboring Iraq to impose new political and economic restrictions that might otherwise arouse opposition here.

In a radio message to the nation on President Carter's decision to break of diplomatic relations and curtail trade with Iran, Khomeini said: "If Carter has done one thing during his life which it can be said is to the benefit and interest of the oppressed, it is this very cutting of relations between a nation risen for liberation from the grip of international plunderers and a world predator plunderer. We consider this cutting of relations a good omen because it is a reason for the U.S. government to give up hope about Iran."

Khomeini combined his response to the U.S. sanctions with his harshest attack yet on the Iraqi government of President Saddam Hussein, calling for the overthrow of his "inhuman and illegal regime." (See related story, Page A16.)

Coinciding with the imposition of U.S. sanctions, Iranian authorities announced sharp restrictions on their citizens' travel abroad, imminent executions for alleged saboteurs in the autonomy-seeking province of Khuzestan, a ban on demonstrations at the predominantly leftist Tehran University and a crackdown on unemployment protests, work slowdowns and strikes.

In an evening television address, Bani-Sadr called for massive demonstrations against the United States all over the country Friday and appealed for "backbreaking work" by Iranians to rebuild the country's economy. a

He told Iranians that there was no reason to worry about the U.S. sanctions because Iran had all the food and medicine it needed.

"The American action can have little effect," Bani-Sadr said. He called it "a good opportunity to gain economic independence" and said it came at a time when "the country needed uniformity and unity."

Western diplomats said the sanctions did not appear to go much beyond the status quo, since U.S.-Iranian trade and diplomatic relations have been virtually at a standstill since shortly after the Nov. 4 U.S. Embassy seizure by militant Moslem students.

They said however, that the sanctions would have a substantially more detrimental effect on Iran if there is an armed conflict with Iraq and the Iranian Army needs spare parts for its equipment, which has been largely supplied by the West, especially the United States.

More damaging to the Iranian economy would be a decision by Washington's Western allies to join the sanctions, but it is not immediately clear here whether they are ready to do so. In fact, there has been some indication in Tehran that NATO countries have advised the United States against imposing sanctions and may be reluctant to go along with them.

Oil Minister Ali Akbar Moinfar threatened an Iranian oil boycott against U.S. allies who go along with the sanctions.

Diplomats said the sanctions seemed likely to strengthen the hand of the militant embassy captors and their hardline clerical supporters against the enfeebled secular government of Bani-Sadr.

Foreign Minister Sadegh Ghotbzadeh said upon leaving one of a series of Revolutionary Council meetings today that the U.S. sanctions "will not have the least effect upon the condition of the American hostages."

He added, "We must all work and work hard; particularly in our factories the slowdowns must end."

Revolutionary Council secretary Ayatollah Mohammed Beheshti, who also leads the hard-line Islamic Republican party, said that tackling Iran's internal problems was far more important now than the country's with the United States.

At a joint meeting of the council and Iran's governors-general, a suggestion was made to declare a "state of extraordinary situation" in the country to deal with the U.S. sanctions by embarking on "a holy war for economic independence." Officials emerging from the session, however, made it clear that the focus of the efforts would be to correct Iran's post-revolutionary economic ills by producing more, consuming less and curbing many Iranians' inflated expectations of prosperity under the new regime.

Since the revolution, the country's economy has been plagued by unemployment, flight of capital, loss of experienced top- and middle-level managers and militant labor demands for management controls and exorbitant wage increases.

The pretext of combating U.S. economic sanctions provides a perfect excuse for authorities to demand greater public participation and sacrifice to deal with these internal economic problems, analysts here said.

"My feeling is that the American sanctions are tough, but probably won't break anyone here for the time being," said one Western-educated Iranian chemist.

He appeared more concerned by the breaking of diplomatic relations, fearing that it may cause hardship for a 21-year-old sister who recently started university studies in the United States.

"I'm worried about how I can get money to her now, or whether she can stay there," he said. "But I don't think this kind of thing is going to make the students or Ayatollah Khomeini hand over the hostages."

Said a European diplomat of the sanctions' potential economic impact on Iran. "I was not very struck by any great difference from the present situation. Even if you include foodstuffs, there aren't many of them, just a bit of chicken feed -- literally."

One of the few U.S. commodities that has continued to come into Iran, according to diplomats, has been feedgrains for Iran's poultry industry.

Much of the continuing U.S. imports come through third parties, they said, and some are smuggled from Persian Gulf countries. The volume of Iranian non-military imports from the United States, however, amounts to nowhere near the billions of dollars a year before the revolution. One diplolmat guessed that about $5 million a month worth of U.S. goods were still coming in.

"Sanctions would certainly cause some inconvenience," another diplomatic source said. "The visa thing doesn't hit Ayatollah Khomeini, but it hits a lot of people here," he added, referring to the U.S. cancellation of unused visas held by Iranians.

"As for what is no doubt concerning America, the response of its allies," another European diplomat said, "we've all advised against such measures and I don't really think Carter can expect much in the way of active support."