Senior U.S. and allied officials, under pressure from Washington for economic action against the Soviet Union, today opened a two-day meeting designed to update and toughen the inventory of high-technology goods blacklisted for sale to Moscow.

The session of Cocom, the Coordinating Committee for Multilateral Export Controls, coincides with a campaign by the Reagan administration to counter what U.S. officials describe as a concerted Soviet program to obtain the latest Western technology to improve the Red Army's capabilities.

As a result, the usually obscure organization, based in a nondescript building, has become a focus of attention in the administration's drive to organize an allied response to the Soviet role in Poland.

The United States has clearly indicated it wants Cocom members --Japan and the NATO allies, except Iceland--to cut back on sales of advanced equipment, even nonstrategic, that could bolster Soviet might by direct military application or by freeing other resources for military.

"We will present new evidence to our allies on how the Soviet Union and Warsaw Pact are using Western technology to strengthen their offensive military capabilities," Defense Secretary Caspar W. Weinberger wrote in The Wall Street Journal last week.

Lawrence Brady, assistant secretary of commerce for trade administration, said in this context recently that the United States will pursue efforts to have Western European governments reduce or cancel a $16 billion pipeline deal to ship Soviet natural gas from Siberia to the capitals of Europe.

Diplomatic sources in Paris, however, suggested that U.S. representatives are laying out American desires and explaining the administration's fears rather than demanding action. Their caution reflects European reluctance to allow the Polish crisis to become a reason for tightening controls on lucrative trade with the Soviet Union.