A mixture of business fear, diplomatic reserve and political hope is the complex European reaction to the American antidumping system for curbing steel imports, approved by President Carter in Washington on Tuesday.

The European Common Market's executive body, which today approved its own response to the international steel crisis, remains reserved on the potential impact on Europe of the trigger price plan prepared by Treasury Undersecretary Anthony Solomon, according to market sources.

The U.S. price scheme, which sets the anti-dumping trigger level within 5 per cent of Japanese production costs, "appears to correspond to what was discussed in Washington and decided in Paris," was the hopeful verdict of top EEC steel negotiator Viscount Etienne Davignon. He referred to his November talks with Robert Strauss, the President's special trade amabassador and to the agreement reached by the world's major steel exporting countries in the French capital last week.

But not until we know what japanese costs really are will we know what it means for us, say EEC officials, who fear a deflection of world exports toward Europe, where prices are an estimated 10 per cent to 30 per cent belowe levels for Japanese steel products.

More optimistically, they hope that higher American import prices will ease the house on cut-price exports to the U.S. from Europe, whose steel producers have been engaged in what one EEC official admitted is a price war on the belea-tiered American market.

This admission appears to make good the claim in the Solomon report that the global slump in steel demand and the substantial excess capacity in the industry have led to aggressive exporting by foreign steel makers, in particular those in Japan and the European community.

But there is no hiding the fears of European industry at the U.S. move. Facing massively increased pressure from cheap East European imports. Common Market steel makers complain the Solomon plan will mean the loss of a major external safety value, as industry sources here describe the U.S. market.

Describing the European steel situation as catastrophic, one industry official affirmed that "we are against this export limitation," and claimed that the U.S. Justice Department is itself opposed to the trigger price scheme on anitrust grounds.

This uncertainty is compounded by contradictory views here of the impact of the U.S. anti-dumping scheme on existing complaints levelled by American steel companies against European competitors.

Industry feels that U.S. import control move will mean the withdrawal of most complaints, according to sources here. However, the verdict of EEC aides is that no automatic anmesty is necessarily involved.

Leading focuses of concern are National Steels complaint against eight EEC steel makers, and the Armco dumping action just launched against the British Steel Corp., the state-run giant enjoying a virtual monopoly situation in the U.S.

The policy response to the Carter steel plan by the Common Market, where industry is now drastically limited to less than 60 per cent operating rates, has been swift and purposeful. It has approved a scheme calling for wide-ranging export limitation accords with the market's major external suppliers and urging accelerated anti-dumping measures against exporters not respecting their terms.

East European countries will be a major target in this round of talks, which began last week when Japan krenewed a pledge to limit its 1978 exports to the nine EEC countries to 1.3 million tons. A strict quota system seems certain for Communist countries, whose exports to Western Europe have climbed dramatically from 150,000 tons per month in 1976 to 250,000 tons this year, complain industry officials.

"We will have no pity on those who do not play to the rulebook of international cooperation" is the stark warning of one EEC aide, adding that the market will deal with price-cutters blow for blow. Other countries expected to be involved in export restraint talks include South Korea, South Africa, Spain and Sweden.

The Common Market plan also orders two 5 per cent hikes in domestic reference prices to be made early next year to bring EEC prices nearer levels in the U.S. But there will be no European trigger price system - "Our prices are too low to make that necessary," market aides say.

The EEC's longer term hopes are pinned on a multilateral solution to the international steel crisis, to be worked out with other leading steel producers. Sources here say that the market is shortly to make proposals for a joint crisis managemet system and its rapid application.