President Carter extended informal recognition and an offer of cooperation yesterday to the government emerging in Iran from the Islamic revolution that the Carter administration had sought for nearly a year to prevent.

As the president told a Washington news conference that the U.S. embassy in Tehran was already "consulting very closely" with the government appointed by Ayatollah Ruhollah Khomeini, U.S. officials here continued to examine urgently contingency plans for the forced evacuation of the estimated 7,000 Americans still in Iran.

Armed bands of Khomeini's followers are picking up Americans, including military personnel, for questioning, and releasing them unharmed, according to State Department reports that have greatly increased official concern about the safety of Americans.

Carter's relatively conciliatory remarks about Khomeini's success in deposing Prime Minister Shahpour Bahktiar on Sunday reflected that concern, U.S. officials said.

The remarks also openly reflected the sudden changes of fortune for the United States, which for four decades held a privileged position in Iran but which now finds itself dependent on the new revolutionary government named by Khomeini for the safety of Americans in Iran.

"The followers of designated Prime Minister [Mehdi] Bazargan have been very helpful in ensuring the safety of Americans," Carter said in outlining his "continued hope for very productive and peaceful cooperation with the government of Iran."

At a later State Department briefing, spokesman Hodding Carter said the United States was not extending formal recognition to Bazargan's government for the time being, but the administration was dealing "with the reality on the ground" by cooperating with the Bazargan government.

The answer appeared to sweep away the administration's previous insistence on constitutional change and some form of continuity flowing from the rule of Shah Mohammad Reza Pahlavi, who installed Bakhtiar before leaving the country on Jan. 16.

Hodding Carter said he could not tell reporters if the State Department still considers the 1906 Iranian constitution is in effect or if the shah is still head of state in the U.S. view.

In related developments:

A detachment of 69 Marines dispatched by the Pentagon Sunday to stand by at Incirlik, Turkey, for possible duty at the U.S. embassy in Tehran was held up at a U.S. fueling station in the Azores because Turkey declined to give immediate clearance for the Marines.

Asked at his news conference about attacks on the Soviet Union by Chinese Vice Premier Teng Hsiaoping during his visit to the United States this month, President Carter said that in "some areas" he disagreed with Teng's assessments of the Soviet Union, which Carter said has "negotiated in good faith" for a strategic arms limitation treaty (SALT).

Carter confirmed that he had lectured foreign policy aides last week over contacts with the press. After reaching a decision, "I expect my policy to be carried out with loyalty and with enthusiasm," he said.

Iran dominated the president's news conference, his 44th in two years. He began the conference with a brief announcement that listed U.S. goals in Iran as ensuring the safety of Americans there, minimizing bloodshed and ensuring that Iran "is militarily capable of protecting her independence and her territorial integrity."

The other U.S. goals listed by Carter were preventing interference or intervention in Iran by outside powers and the honoring of the will of the Iranian people. He did not spell out any steps the United States would take to accomplish these goals.

As the shah's rule crumbled over the past year, Carter reluctantly shifted his expressions of "total support and confidence" from the monarch to the Iranian constitution and then to the shah's appointed stand-in, Bakhtiar. As recently as Dec. 12, Carter criticized Khomeini without naming him for issuing "uncontrolled statements that encourage bloodbaths" in Iran.

White House efforts included sending U.S. Air Force Gen Robert Huyser to Iran to encourage the Iranian military to back the constitution rather than a coup or the Islamic revolution.

Acknowledging that "we have worked closely with the shah when he was in office" and that "we have worked with Bakhtiar," the president said "we will attempt to work closely with the existing government." He noted that Bakhtiar and the parliament resigned over the weekend, leaving Bazargan in place.

Tass, the official Soviet news agency, announced that the Soviet Union had extended formal recognition to Bazargan's government, which is still being formed.

Hodding Carter said at the daily State Department briefing that the question of formal U.S. recognition had not yet arisen. "We have relations with countries" rather than governments, he maintained.

A State Department official who declined to be identified added that a diplomatic relationship with Iran continues automatically "as long as it seems that the other government wants it to continue." This seems to be the case with Bazargan's government, he said.

The sensitivity over possible evacuation action was reflected by the refusal of Pentagon spokesmen to discuss the matter with reporters.All queries were referred to the White House, where an official said that U.S. aircraft were not presently being readied for emergency procedures.

Pentagon and State Department spokesmen declined to discuss the whereabouts of six HH53 passenger-carrying helicopters that were shifted from England to a position closer to Iran on Sunday for possible emergency use. Turkish officials in Ankara said that the helicopters would be permitted to station there, but they said they had vetoed plans for the detachment of Marines.

Conceding that he had called in high-ranking officials of the State Department, the National Security Council staff and the Domestic Council last week to "insist upon a degree of teamwork once a decision is made," Carter maintained that he was not restricting contact between the Press and his administration.

"I have admonished" members of the administration "to have a free expression of opinion and let me have their individual opinions up until the time I make a decision" and "once I make a decision to comply with it," Carter said. "The only option" for someone not willing to comply "is to resign."