Sen. Daniel Patrick Moynihan (D-N.Y.) is right. He says we are paying, in the Persian Gulf, the first heavy wages of the Reagan administration's crazy sales of arms to Iran in violation of everything Congress and our allies had been led to believe was U.S. policy.

It was not by coincidence that immediately after the news of the arms sale broke in November, the Kuwaitis turned to Moscow for protection of their tankers in the Persian Gulf. The Kuwaitis then adroitly played on Ronald Reagan's natural confrontational instincts to extract a commitment for tanker-escort services under an American flag.

Thus, Moynihan argued the other day in The New York Times, ''This faithless, doomed {U.S.} conspiracy {with Iran} has reached far beyond mere disgrace. It has threatened the balance of power.'' So how is it that in Venice, Reagan could extract from our allies (whose dependence on Persian Gulf oil is far larger than ours) no more than the limpest sense of urgency and the lamest expressions of even moral, let alone material, support?

To understand, you have to look beyond last November to the last time Reagan invited allies on a multinational peacekeeping venture. It was in Lebanon, in 1982. That too, began with an ''escort'' mission -- to extract PLO fighting forces from Lebanon before the Israelis reduced it to rubble. Then came the carnage at the Palestinian refugee camps, and the U.S.-French-Italian contingents went back to Beirut.

For the United States, it was in the nature of a guilt trip. We thought we had a deal with the Israelis to protect the camps. Instead the Israelis stood by and watched. But that was not reason enough; so the joint force was turned into a ''buffer'' while diplomacy addressed Israeli and Syrian withdrawals so that Lebanon could reassemble its shattered fragments and become a country again.

When this was revealed as a hopeless undertaking, a geopolitical overlay was quickly applied. At stake, said Ronald Reagan, was not only Arab-Israeli peace but the global power balance. The battleship New Jersey would set things right.

You know the rest: the bombing of the Marine compound with heavy casualties and the ignominious American pullout on short notice, leaving our partners to wonder what had happened to those high purposes and how they had ever got caught up in them. Now they are being asked to endorse (if not actually join) another U.S. ''escort'' mission -- undertaken unilaterally, with almost nobody knowing about it (except the Kuwaitis) in advance.

Once again, they see a confused, conflicted Congress compounding a perception of U.S. irresolution by wringing its hands and wondering whether to invoke the War Powers Act. The smart ones in Congress know that, as a practical matter, any effort to force the administration to renege now on its commitment to Kuwait would be a clear win for the Soviets. That would leave the Democrats wide open to a ''who-lost-the-Gulf'' election-year debate.

Yet congressional critics, no less than our allies, have no wish to sign on blindly to a set of Reagan administration objectives that are at least as mercurial as those in Lebanon. ''Freedom of navigation in international waters'' is hardly a convincing aim when its enforcement is limited to 11 Kuwaiti tankers. By protecting Kuwaiti tankers against Iran, the administration then argues, we will be offering some inducement (Kuwait being an ally of Iraq and the target of assorted Iranian pressures) for the Iranians to negotiate.

But Iraq has done more than Iran to make the Persian Gulf a shooting gallery. Only a fraction of the almost 100 ships hit since the ''tanker war'' began three years ago have been Kuwaiti vessels. There has been no increase in the scarcely noticeable effect of any of this on the flow of Persian Gulf oil.

Finally, there is the argument that the United States had no choice the minute the Kuwaitis decided to work both sides of the street. There's truth to that: once again we are witnessing the power of an impetuous, imperious president to commit American forces in a way that cannot be readily reversed by Congress without making matters worse.

A prudent administration would not exploit Congress' dilemma. Extricating ourselves from a high-risk plunge into the Persian Gulf is going to be a lot harder than bugging out of Lebanon, where the stakes and risks were not nearly so high.

This makes it all the more important for the administration to understand what it was that it lost in Lebanon and in the arms sales to Iran. It was not some macho image that can be restored by tough talk and gunboat diplomacy. It was the kind of trust and confidence that can only be restored by a careful, collaborative effort to identify realistic purposes that the American public, Congress and friendly foreigners can reasonably be expected to support.