ISN'T IT TIME to set the Cyprus issue to one side in the tangled affairs of the eastern Mediterranean and to get on with restoring firm American ties with Turkey and Greece? Does not this approach promise better results in Cyprus itself than four years of direct diplomatic assault have produced?

We think so. We think that few American policies have been more earnestly motivated, and more thoroughly discredited, than the failed effort to force Turkey to roll back its invasion of Cyprus by imposing an arms embargo. Cyprus has received no benefit whatsoever from it. The American position in that strategic corner has steadily deteriorated. Two American presidents have been undercut.

The congressional "Greek lobby," which has dominated sucessive administrations on this issue, remains unreconstructed. It holds that the best way to pry the Turkish army off the island and bring a settlement is to keep the pressure on Ankara. Increasingly, however, other legislators, including now a House International Relations Committee majority, suspect that the embargo merely humiliates Turkey and that the Turks - curse them as you will - will not budge on Cyprus while this embargo stays in effect. We agree.

Deputy Secretary of State Warren Christopher is in Ankara today. If he is not trying to see whether Turkey, in the event that the embargo were lifted, would move promptly on its own toward a fair Cyprus settlement, he has wasted a trip. Great delicacy is required. The Turks can't countenance being seen to be acting under pressure. The Greek government must not be exposed to opposition charges that, for the sake of NATO, Greek interests on Cyprus are being sold out. But perhaps a bargain can be struck.

Cyprus is not, after all, the issue it was. Greek Cypriots, foresaking the Palestinian example of the open wound, have built a successful new life in the north, a federal system that would leave the Turkish Cypriot minority will protected, and an end to the Turkish occupation and to the specter it raises of an eventual Turkish grab of the whole island. Surely the new Turkish government of Bulent Ecevit, a fair-minded man, can grant as much - if the embargo's affront to Turkish nationalism is eased.

A settlement on Cyprus would warm the climate in which Athens and Ankara could tackle their difficult Aegean Sea dispute. It could repair the American position in a vital region. But it cannot even be considered if the Congress will not grant that the time for a new look is at hand.