The West German Ministeer of Economics predicted here yesterday that Arab oil producers will steadily reduce the amounts of oil they sell to industrial countries, "and they will do this at prices which just about allow us to keep going."

This grim assessment was offered in a National Press Club address by Otto Graf Lambsdorff, who is in Washington for consultations with American officials after a recent visit to the Persian Gulf states.

Lambsdorff said the more moderat oil producers, unhappy at having to act this way, are no longer in a majority. "But they, too, are faced with the problem that they already supply us with more (oil) today than is actually in their own long-term interest," he said.

Lambsdorff reported he had pressed the Arab leaders to follow a pattern of "smoother, less sharp," but more regular price increases, rather than the "sudden spurts which lift the world economy of its hinges every few years."

The German cabinet officer said he found the Arab countries fearful of Soviet aggression in Afghanistan, a development he stressed is also of deep concern to his government.

"If we were cut off from sources of oil on both sides of the Persian/Arabian Gulf, we in Europe could shut up shop," Lambsdorff said bluntly. "Great Britain might hold out a little longer, but not much longer."

As things stand, higher OPEC prices have dimmed economic prospects for West Germany and all of Europe, he said.