French Foreign Minister Jean Francois-Poncet ended three days of top-level consultations here yesterday, approving the Reagan administration's "openness toward dialogue with the Soviet Union" in the face of summit signals from Moscow.

The French minister, declaring that relations between Washington and Paris are off to "a good start" in the new administration, portrayed the new administration's East-West policy as "well balanced" and thus acceptable to France.

After a meeting with President Reagan at the White House, Francois-Poncet said the attitudes and analyses of the two countries regarding the Soviet Union are very similar. He summed up current French policy in two words: firmness and dialogue.

The firmness was expected, heralded by the trumpet blasts against the Soviets from Reagan, Secretary of State Alexander M. Haig Jr. and other high administration figures. The willingness for dialogue was less clear, which gave additional significance to Francois-Poncet's remarks after his lengthy private talks.

At the State Department yesterday, spokesman William Dyess succinctly outlined three U.S. conditions for a summit meeting with the Soviets. Such a conference, he said, "should have a clear purpose, be carefully prepared, and there should be reason to believe there would be concrete achievements."

By setting out the conditions, the new administration created a situation just the opposite of that of four years ago, when the Carter administration made clear its eagerness for a summit meeting with Soviet leader Leonid I. Brezhnev only to run into Soviet conditions that such a meeting crown a specific achievement, such as signing of the strategic arms agreement.

The French foreign minister, while saying that the Reagan administration's reports of communist-backed arms shipments to El Salvador were "no surprise" and that France stands against such "external interference," projected a much different emphasis in this area than did Washington officials.

"Social conditions in that part of the world are terribly unequal, and reforms are necessary," Francois-Poncet told reporters. He said that it would be a mistake not to realize that in the end the solution must be political, but that the solution cannot be achieved while arms flow from outside.

The Reagan administration has given a notable military edge to its public and private statements about El Salvador, with little emphasis on economic and political reform.

Regarding transatlantic consultations, the French foreign minister was assured by Reagan, according to White House press secretary James S. Brady, that "there would be no surprises" in the French-American relationship.The Paris official appeared to be relieved in the light of irritating surprises, some of them from each side, during the Carter administration.

The discussion of alliance dialogue came as the directors of the leading foreign policy study councils of the United States, Britain, France and West Germany called in a report for a new transatlantic bargain in which Europe assumes a greater burden as well as a greater share of decision-making in international crises.

The joint report by the four study councils, including the U.S. Council on Foreign Relations, said the western alliance in the years ahead faces some of its most dramatic challenges in the Middle East and other areas of the Third World.

Rather than expand the North Atlantic Treaty Organization to peripheral areas, the report proposed the creation of groups of "principal nations" for joint assessments and crisis management of emergencies outside Europe. Such a group to deal with developments in the Persian Gulf and Southwest Asia should be "immediately" established, with the United States, Britain, France, West Germany and Japan as participants, it said.

The report also endorsed the need for a western military force near the Persian Gulf, with European participation and support adding to the American "rapid deployment force," and western aid and encouragement for rebel tribesmen fighting the Soviets in Afghanistan.