Brussels — ''What is certain is that the United States and Western Europe are headed for a showdown.''
This is how a European Community spokesman responded July 20 to what West European governments see as increasing dogmatism and inflexibility in Reagan administration thinking.
''We've issued communique after communique condemning American policy in the toughest language possible between friends. Now its time to back up our words with action,'' the official said.
And West European officials have moved quickly over recent days and weeks toward taking a tougher, hard-line approach on transatlantic disputes. This threatens to widen further the growing gap between the Atlantic allies.
Conflicts between the US and several Western European countries over various issues ranging from American restriction on the sale of European equipment for the Soviet gas pipeline to stiff US duties on European steel imports, have been simmering, sometimes boiling, for months.
But only in the past few weeks have the Europeans shown a willingness to get tough with their ''American friends,'' rather than to continue to put emphasis on efforts to change US policy with words and gentle prodding.
The soundest evidence yet of this new mood came at a meeting of European Community (EC) foreign ministers July 20 - the second such meeting devoted almost exclusively to deteriorating commercial relations between the US and Europe.
''At the meeting, I noticed an increasing determination all around the table to stand tough against the Americans,'' the president of the EC, Danish Foreign Minister Kjeld Olesen told journalists July 20. ''This psychological aspect must not be underestimated.''
Etienne Davignon, EC industry commissioner, echoed the point, saying ''there is no longer any question of the EC or the national governments kowtowing to American pressure and giving way.''
What both officials had in mind - among other things - was the recent decision by the British government to allow British companies, with contracts to supply equipment for the Soviet gas pipeline, to circumvent the US ban on such sales. The ban was announced by President Reagan several weeks ago in protest against the continuing Soviet involvement in the military crackdown in Poland.
Attempts are still being made by several European governments to persuade President Reagan to reverse his decision. Raising the issue in talks this week with US Secretary of State George Shultz in Washington, will be a parade of European officials including West German Chancellor Helmut Schmidt, Italian Foreign Minister Emilio Colombo, and British Foreign Secretary Francis Pym.
But the Europeans now understand that Mr. Reagan will not change his mind until - as one high EC official put it - ''there is a substantial change in the Polish situation.''
Therefore, national governments have begun to prepare dossiers challenging the legality of the US action. Since the matter mainly affects firms in West Germany, Britain, and France, it could end up in the International Court of Justice in the Hague or in European courts, where, according to may experts, the Europeans would win.
''We have tried to explain to the Americans what these lost contracts would mean in terms of lost jobs,'' a frustrated Wilhelm Haferkamp, the EC commissioner for external relations, said July 20. ''But they don't seem to have understood the possible political and social repercussions.''
On steel, the Reagan administration has remained rigid too, forcing the Europeans to respond in kind. Months of negotiation between the EC and the US Commerce Department on limiting European steel imports to the US ended in failure last week. And while bilateral relations between the US and individual steel producing countries continue, the EC foreign ministers July 20 authorized the Commission to look into possible retaliatory measures to be employed against the US if the latest round of negotiations fail.
Few analysts will venture a prediction on how the new European mood of ''standing tough'' against the US will work out. But they do agree that a showdown is imminent.