THE PLIGHT of the American hostages in Iran is a painful reminder of the vulnerability of the most powerful nation on earth. Yet even in this crisis, where a concern for its citizens' lives makes it hard for the United States to apply its superiority in conventional forms of power, we are not entirely without means. The Carter administration is proceeding on that premise and deserves to be encouraged along the way.

The administrations's chief tack seems to be to internationalize the crisis: to frame it in terms that touch the interests of other nations (the inviolability of diplomatic persons and places), and on that basis to appeal for their support. One result of this effort became evident when a unanimous United Nations Security Council publicly appealed for release of the hostages. Other nations and other parties, including Pope John Paul II, have made parallel appeals. Ayatollah Khomeini's isolation is all but complete.

That he is not at all pleased to be identified as an international pariah is apparent. The ayatollah has undertaken an extensive campaign of public diplomacy -- to prove that the hostages are alive and reasonably well and to win support for the Iranian demand to have the shah returned from his New York hospital bed for trial in Tehran. In international eyes, however, the issue of the shah is quite apart from the issue of the hostage-taking. Even governments sympathetic to the ayatollah's revolution have rejected his blackmail tactics.

The exhilaration of some Iranians in staging this daring and symbolic rebellion against the United States -- the only country of those that have offeredd sanctuary to the fallen shah to have had its embassy seized -- should not be underestimated. Yet reports of a demonstration by the unemployed in Tehran and of a new military campaign by Iran's Kurdish minority indicate some of the difficulties the ayatollah courts by continuing down the confrontation path. American food exports to Iran, which provide the crucial margin of social pacification for the regime, apparently are continuing, at least for now. Yesterday, however, the Carter administration removed perhaps the sharpest arrow left in the ayatollah's quiver, the threat of an oil embargo, by deciding on its own to stop importing Iranian oil. The deportation proceedings that now hang over the Iranian students who have violated the terms of their visas constitute yet another reversal.

Presumably, Iran's diplomats in this country are reporting (that's the best reason to leave them in place) what is obvious to the rest of us: that such pressure as there is on Mr. Carter is coming not from those who would have him surrender the shah but from those who would have him take an even tougher line.