President Carter, admitting that he cannot predict an early end to the U.S. confrontation with Iran, said yesterday he will not postpone his campaign for economic sanctions to force the release of the American hostages in Tehran.

The president called the captives' 78-day ordeal "an abhorrent act, supported by the Iranian officials," but he also underscored his administration's argument that Iran's real enemy is not the United States but the Soviet Union.

"What we want is a unified Iran, not fragmented," Carter said in an interview on the television program "Meet the Press" (NBC,WRC)."We want a stable and independent Iran, and we want a secure Iran."

Since the Soviet invasion of Afghanistan, the Carter administration has given top priority to containing Soviet influence in the vital Persian Gulf region by trying to rally the support and cooperation of the area's Moslem countries.

That has caused the administration to mute the harsh rhetorical tone it had taken toward Iranian leaders in the early days of the hostage crisis and to soft-pedal such tactics as hinting at the possibility of a naval blockade against Iran.

Instead, the administration lately has been stressing that, except for the hostage issue, it has no quarrel with Iran and that resolution of the hostage probelm could pave the way for U.S. assistance to Iranian efforts to fend off Soviet pressure.

In the interview, Carter took the same line, saying: "There has been obviously a new element introduced into the Iranian hostage crisis in recent weeks with the Soviet invasion of Afghanistan."

He added, "my belief is that many of the responsible officials in Iran now see that this major threat to Iran's security, and the peace of Iran, is becoming paramount, and that there will be an additional effort on their part to secure the release of the hostages and remove the isolation of Iran from the rest of the civilized world."

But, when Carter was asked whether this position might induce him to defer the U.S. campaign for an economic squeeze on Iran, he replied: "No, those sanctions will be pursued by ourselves, unilaterally, and joined in by as many of our allies as will agree."

The move for sanctions was worked out in the early stages of the Iranian crisis and originally was pursued by the United States in the United Nations Security Council. However, the attempt to impose sanctions under a U.N. mandate was derailed by the Soviet Union's veto of the resolution in the Security Council.

The subsequent U.S. decision to keep up its own economic pressure is known to have caused misgivings among some allies and within the policymaking circles of the administration.

However, Carter is understood to have decided to go ahead with sanctions because dropping them, after they have been given so much stress earlier, would undermine his credibility and expose him to charges of not being firm enough in pursuing the release of the 50 American hostages.

"I don't know when the hostages will be released," Carter said, "but we maintain our intense interest in it. We will maintain our commitment to every possible avenue to carry out the policies I have described, and we will maintain as best we can the full support of the rest of the world and concerted pressure from many sources, including the recent sanctions that we have intitiated against Iran.

"I believe and I hope and I pray they will result in the safe release of our hostages. But I can't predict exactly when."

In the television interview yesterday, Carter was asked several questions about his resolve and whether the Soviet moves in Southwest Asia were prompted by a belief that the United States would not respond.

"We have not been weak," he responded. "We have been firm and resolved and consistent and clear in our policy since I have been in the White House."

He cited his efforts to increase the U.S. defense budget, to strengthen the nuclear and conventional forces of the North Atlantic Treaty Organization and to resolve such peace-threatening disputes as the Arab-Israeli conflict.

In respect to the situation in Southwest Asia, Carter noted the new U.S. offers to aid Pakistan in resisting Soviet encroachment and the administration's determination to "maintain an increased level of naval forces in the northern Indian Ocean and the Persian Gulf region .... "

The president cited the 1959 U.S. military agreement with Pakistan and said: "We are committed to consult with Pakistan and to take whatever action is necessry under the constitutional guidelines that I have to follow as president of our country to protect the security of Pakistan, involving military force, if necessary."

Although administration officials have invoked this 1959 agreement repeatedly in their post-Afghanistan statements, it contains several loopholes leaving unclear the precise way in which the United States would have to respond if Pakistan came under attack.

Beause of that lack of clarity, Pakistani President Mohammed Zia ul-Haq last week called for transforming the agreement into a treaty guaranteeing his country's integrity and independence. However the administration rejected Zia's request on the grounds that a formal U.S.-Pakistani treaty would not be feasible.

Carter added, "We are now exploring with some intensity the establishment of facilities for the servicing of our air and naval forces in the northern Indian Ocean, Persian Gulf region.... We are concentrating on them now with an increased level of commitment because of the Soviet invasion of Afghanistan."

The president is expected to devote the major part of his annual State of the Union message Wednesday to discussing the administration's plans in these areas.