A trade group for American steel importers says it may continue efforts to overturn a U.S. embargo on steel pipe and tube purchases from the European Economic Community.

The U.S. Court of International Trade on Wednesday denied a petition from the American Institute for Imported Steel that the embargo be ruled unconstitutional.

The New York-based institute, which is composed of 70 leading steel importers into the United States, said it may appeal the ruling. The group estimated it will cost importers $10 million to store steel they already are shipping or have on order but will be unable to sell until January.

The ban took effect Nov. 29 and continues through 1984. It was imposed after attempts to negotiate restraints with the 10-nation EEC failed.

President Reagan has pledged to reduce imports' share of the American steel market from the current 26.1 percent to 18.5 percent. U.S. Trade Representative William Brock said the agreements would be in place by Dec. 18.

Fred Lamesch, president of AIIS, said the embargo was unlike any other in the past 30 years because it was imposed without warning and applied to steel already aboard U.S.-bound ships.