U.S. national security affairs adviser Zbigniew Brzezinski warned today that support for governments in Central America unwilling to entertain "land reform and social changes" would undermine U.S. efforts to urge restraint on the Soviet Union in Eastern Europe, particularly Poland.

Vigorously defending his own record in the White House, Brzezinski challenged the Reagan administration to come up with better policies than the Carter administration, especially in Central America and East-West relations.

In what amounted to a political testament, before the French Institute of International Relations, he drew a striking comparison between the Soviet attitude toward Central America.

"We have dominated Central America militarily," he said. "We at times have exploited it economically. . . . But we are outgrowing that phase of our history . . . If the workers of Gdansk have the right to demand a decent wage and decent weekly hours, the peasants of El Salvador and Nicaragua have a right to demand their land."

Suggesting that any attempt by the Reagan administration to turn its tough campaign rhetoric about Central America into policy would only undermine attempts to encourage a loosening of the Soviet hold over its Eastern European sphere of influence he said: "It is very difficult to argue that the Soviet Union should restrain itself when a trade union movement manifests itself which doesn't challenge formally party supremacy . . . and at the same time say that we're going to support regimes which oppose land reform and social changes in an area in which we have been dominant."

He called on such Reagan appointees as U.M. Ambassador-designate Jeane J. Kirkpatrick to say what alternative policies they propose to the Carter approach of encouraging moderates willing to undertake social reform, even at the risk of Castroites trying to exploit "the collapse of the existing political orders."

Brzezinski said that the Carter approach is very difficult because it "means the collapse of internal power structures which were connected with our domination, and the question is, what will replace it?"

But if the United States does not continue to display what he called a "new maturity" in the region, "we'll alienate all of Latin America, and that will be a very, very high price to pay for the politics of nostalgia."

The outgoing national security adviser related his remarks to the main theme of a prepared text in which he stressed the need to extend the annual seven-power summits on economic relations into global strategy sessions to meet the Soviet threat. Those meetings of the leaders of the United States, Canada, Britian, France, West Germany, Italy and Japan should be held, he said, to coordinate allied exploitation of such opportunities for peaceful change in the Soviet orbit as the Polish situation.

But he added, such meetings are also "staggeringly urgent" to counteract the Soviet drive in the Middle East and the Persian Gulf. If that "central strategic zone" is lost to the West, he said, "at the very best, Japan and Western Europe will become neutralist; at the worst they'll become subordinate" and the world balance would be "irretrievably altered" in Moscow's favor.

In the text of his speech, he was complimentary toward the Western Europeans. But in his answers to questions, he displayed bitterness about European unwillingness to follow Washington's lead on such issues as the economic and Olympic boycott of the Soviet Union after its invasion of Afghanistan.