GENEVA, DEC. 4 -- One after another, trade ministers stepped to the podium here this week and called on the United States to put its fiscal house in order.

But the paradox underlying the meeting here of the 95 nations that belong to the General Agreement on Tariffs and Trade (GATT) is that many countries fear that the Reagan administration and Congress actually will get together and make meaningful cuts in the U.S. budget deficit.

That would likely cause a contraction in the U.S. economy, which other countries expect would hurt sales of their exports to the United States.

While this would help ease the United States' stubborn trade deficit, which has soared to record heights for four straight years, it could plunge many countries whose growth depends on exports to the United States into economic recession or worse.

For while the budget deficit has brought instability and uncertainty to world financial markets and caused the U.S. dollar to plunge to record lows, it also has fed economic expansion in the United States, which has become the locomotive for world growth in this decade.

This expansion, which took place amid sluggish growth in most other industrialized nations, sucked in foreign products from all over the world.

West Germany became the world's leading exporting nation last year on the basis of sales in the United States, which are still growing, totaling $20.4 billion for the first nine months of 1987. The United States is also the biggest buyer of goods from Japan, whose exports to the United States totaled $64.5 billion in the first nine months of the year.

But the greatest impact of a slowdown in the U.S. economy and the accompanying cut in imports is expected to be felt by newly industrialized countries (NICs) of the Pacific Rim, such as South Korea and Taiwan, and the Latin American borrowing nations trying to export more to earn funds to pay interest on their more than $400 billion in debts.

U.S. Trade Representative Clayton K. Yeutter pointed out here Tuesday that the United States takes two-thirds of all manufacturing exports from the world's less developed countries.

He said LDCs must "make a strong effort" to sell their products elsewhere and countries in Western Europe and Japan have to buy from Third World nations.

"That's why we have to speed up our economic growth," acknowledged Willy de Clercq, trade minister of the 12-nation European Communhity.

He said that the rest of the industrialized world must take part in sharing the burden of economic growth to pick up the slack caused by the contraction of the U.S. economy.

There will be plenty of slack to pick up.

The fast growth of the Pacific Rim countries is the envy of the rest of the world. But this growth largely has been fueled by sales to the United States, and there are concerns over the possible social, economic and political repercussions of a U.S. slowdown.

Many analysts believe that social stability has been maintained by fast growth in that region, which provided for the kind of full employment that tamps down unrest.

They are especially concerned over the possibility of unrest in Malaysia, already unsettled by conflict between Malays and a large Chinese population, and in Korea, which is in the midst of a tough transition from military rule to a democraticly-elected government.

Despite the tough choices that awaits them, most officials here agreed that that the U.S. budget deficit must be cut, no matter how much it hurts, for the future of the world economy.