Britain ended many of its wartime restrictions on shipping in the region of the Falkland Islands today and made clear that it is interested in lifting economic sanctions on Argentina as soon as possible.

Prime Minister Margaret Thatcher announced the move on shipping, ending the Total Exclusion Zone of 200 miles around the Falklands that Britain had imposed April 30 at the height of the South Atlantic crisis. She said Britain had requested that Argentina not send military craft within 150 miles of the islands "to minimize the risks of misunderstandings or inadvertent clashes."

Her statement said that Argentine civilian air and sea transports could use this zone "by prior agreement" with British authorities. The immediate vicinity of the Falklands remains closed, she said, for safety reasons.

Finally, the statement says that a May 7 warning to Argentina, that any ships or aircraft found more than 12 miles from the coast would be regarded as hostile, "no longer applies." This softening of previous restrictions would permit civilian movement while maintaining military vigilance.

An Argentine Foreign Ministry communique issued tonight in Buenos Aires said the British request amounted to a continuation of the blockade, The Associated Press reported from London.

The Argentine Foreign Ministry said it continued to reject "the existence of zones of exclusion or limits of any kind in seas that pertain to Argentine jurisdiction and . . . any incident that results from their establishment will be the sole responsibility of the United Kingdom."

The ministry also reaffirmed its position that, "as is demonstrated by the attitude assumed by Great Britain, a definitive cessation of hostilities does not exist in the zone, but a de facto suspension of the same (hostilities)."

The British government's announcement is in keeping with its intention to ease its state of belligerence with Argentina while not departing from its refusal to discuss the sovereignty of the islands or their long-term future.

Toward the goal of resuming ties, officials said the lifting of economic sanctions on Argentina--which include freezing of Argentine assets--is actively being considered. The difficulty is in assuring that Argentina will do likewise. Since the end of active hostilities in mid-June, the British have sought formal word on ending belligerence and restoring ties.

The Argentines have been unwilling to make such gestures and they only tacitly acknowledged last week a British assertion that the war was ended. At that point, Britain returned its last Argentine prisoners.

The British, who say economic sanctions have hurt both countries, are interested in ending all sanctions but those on arms. For the time being, however, officials say they are not in touch with the Argentines on the sanctions issue. Most Anglo-Argentine contacts since the war have been through the Swiss government.