The United States has defused a potential source of diplomatic tension with its West European allies by softening its stand on limiting their dependence on imports of natural gas from the Soviet Union.

A communique issued here today following a meeting of the 21-member International Energy Agency announced that an effort would be made to avoid "undue dependence" on any one source of gas imports. But it failed to set any overall limit to such supplies, as originally suggested by the United States.

The compromise formula effectively represents a further climbdown by the United States in its opposition to the construction of the 3,400-mile pipeline linking Siberia to Western Europe. The Reagan administration announced last November that it was lifting sanctions against companies involved in building the pipeline.

The sanctions were adopted following the failure of western leaders to agree to ground rules for regulating East-West trade at the summit meeting of seven industrialized countries in Versailles last year. A similar meeting is to be held at the end of this month in Williamsburg, and both U.S. and European officials are eager to avoid friction over the same issue.

An American proposal that members of the International Energy Agency agree to restrict gas imports from any one source to 30 percent of their total needs was widely interpreted as aimed primarily at the Soviet gas pipeline. The United States is concerned that the Kremlin could use its gas exports to Western Europe as a means of economic blackmail.

This fear appears to have eased somewhat as a result of the development of other sources of natural gas, particularly in North America and the North Sea. The International Energy Agency communique noted that gas from the big Troll field in Norway is due to be available by next year and encouraged companies to begin negotiations on deliveries as soon as possible.

At a news conference here, U.S. Energy Secretary Donald Hodel expressed support for studies on the feasibility of building a $10 billion pipeline to transport natural gas from Nigeria and Algeria to Western Europe via Spain. He said that he had held conversations about the project with the Spanish foreign minister over the weekend.

Hodel said the United States had dropped its insistence on a 30 percent limit to natural gas imports from one country as part of a process of "political give and take" with other developed countries. He said that it became apparent during the negotiations that some countries would not be able to meet the limit.

Among the western countries most opposed to the American formulation was France, which has strong interests in the Soviet gas pipeline. France is not a member of the International Energy Agency but participated in the negotiations over a compromise as a member of the Organization for Economic Cooperation and Development.

The International Energy Agency communique said the ministers agreed to take steps "to ensure that no one producer is in a positiion to exercise monopoly power" over western industrialized countries. It said that governments would consider "security factors" in assessing the price of gas and attempt to diversify their sources of supply.