PRESIDENT REAGAN faced a certain dilemma in his initial response to the Israeli raid in Iraq. He recognized a need to distance the United States from the raid and to show that he does not have an anything-goes indulgence of Israel. But he saw good reason not to call the basic American attitude toward Israel into question. Mr. Reagan met both requirements. He condemned the raid, made plain that Israel had violated the arms-sales law and suspended for a while the delivery of four new warplanes of the type used in the raid -- to have delivered those planes on schedule, a few days after the attack, would have been lunatic. But he did nothing to alter the United States' continuing role as Israel's sole patron and sole foreign source of arms.

Menachem Begin has been relatively subdued. On the eve of an election, he is evidently disinclined to advertise to his electorate that he has damaged his line to a new American administration and that the raid provoked Mr. Reagan to set what Israelis regard as the extremely troubling precedent of impeding the arms flow for political reasons. Mr. Begin did, however, allow himself to make an invidious distinction between the secretary of defense, whom he accused of recommending an arms cutoff, and "our friend" the secretary of state. This was petty and wrongheaded.

In another context, the general Arab reaction has also been relatively subdued. Some angry things have been said but -- knock on wood -- there are no signs of military or economic reprisals against Israel or the United States. Part of this can be explained by Israel's military superiority and the world oil glut, part by Mr. Reagan's prompt and forthright response and part by Arab relief at having Iraq disarmed. Rejecting whatever contribution American diplomacy may yet make in Lebanon, moreover, would serve no useful Arab purpose.

Any effort to turn up the heat at the United Nations will run counter to the administration's proper distaste for submitting important Mideast matters to a forum long ago discredited on Mideast issues. It will be interesting to see, by the way, whether the United Nations will feel any embarrassment at taking up Iraq's complaint of Israel aggression, even while Iraq continues its eight-month-old invasion of Iran. Certainly Kurt Waldheim, running for reelection as secretary general, shows none.

The absence of an immediate Arab convulsion, however, cannot become an excuse for business as usual -- unless the United States wishes to send the message that it cannot be reached by anything short of a convulsion. Iraq, Libya, some Palestinians and a few others aside, the Arab purpose is less to rail against Israel for this or that than to deepen the American commitment to easing the Palestinian issue so that the area can concentrate on more enduring problems of security and development. Mr. Reagan told the Arab ambassadors on Thursday that "the only answer in the Middle East is to achieve a true peace." To that end, and not simply to the establishment of an anti-Soviet military belt, his policy must now be shaped.