IT IS AXIOMATIC in a crisis that one expects close friends to gather round and render the best help they can under the circumstances, and in the Iran crisis the United States has not been altogether badly served. Notwithstanding their greater reliance on Iranian oil, the European allies have offered useful political and diplomatic support, if a bit tardily and quietly in some instances. They have asserted, with others, the common international interest in upholding the law of diplomatic immunity. They have accepted that the Atlantic alliance, though focused on the Soviet Union, necessarily has a global aspect that makes American honor and credibility in Iran at least in some degree a matter of their own concern.

But of course things are more complicated. The allies are not eager to take the more painful economic steps that the United States has already begun recommending, especially if it turns out that only allies bear a special burden. Some of these steps, like leaning on courts to freeze Iranian assets, look questionable on the merits. But others would seem to most Americans well within bounds, as long as the United States sets the example, demanding no more of others than it is asking of itself.

Then there is Japan, the one close friend whose conduct in the crisis the Carter administration has publicly pronounced wanting. From the entourage of Secretary of State Cyrus Vance, during his consultations with the allies this week, came the sharp complaint that Japan had rushed "with unseemly haste" to buy the Iranian oil the United States is boycotting, and that its banks had "gone overboard" to help Tehran cope with the American-imposed freeze.

No authenticating detail was immediately offered. But Cyrus Vance is a cautious man, slow to take offense, and if even he is offended, that will be enough for a lot of Americans. Japan has long benefited in this country from the idea that it's special case: in its political fragility, its ethnic delicacy, its resource vulnerability, and so forth. By its Iran policy, Japan puts some part of its implicit claim to special standing at risk.

The allies, including Japan, do not like to contemplate the disruptions to their own economies that a prolonged screw-tightening operation, let alone a violent denouement, would bring. They lean to the view that diplomacy, including the avenues they keep open, can be of as much value as their participation in tightening the screws. In this they offer an implicit bargain to the United States, providing their full support as long as something less is sought. This puts the United States in the position of taking as much as it can get in the name of solidarity, and asking for no more in the name of discretion. It is, in brief, not easy to get a little help from our friends.