WASHINGTON, Dec. 13—The Soviet Union's unswerving support of India in the war with Pakistan has caused irritation and disquiet in the Nixon Administration, State Department officials sale today.

The Administration so far has refrained from public criticism of the Soviet vetoes in the Security Council and of Moscow's refusal to join with the United States in exerting pressure on India to halt her advances into East Pakistan. But President Nixon was reliably reported to be irked privately by what he regards as Soviet efforts to obtain unilateral advantages from the war instead of supporting efforts to restore the peace.

Some senior State Department officials have expressed puzzlement at Moscow's willingness to forsake possible dramatic improvements in relations with the United States by its continuing backing of the Indians.

Other specialists, however, said it was “unrealistic” to expect Moscow to act differently from the way it has so far in the crisis.

The specialists said that Moscow had given top priority to its ties with India, mainly to offset China in that part of the world. They added that support for India was more important to Moscow than dividends it might receive here for not opposing the American resolutions in the Security Council.

The Administration has given priority to improving its relations with Moscow in coming months, with the culmination supposed to come with Mr. Nixon's trip to the Soviet Union next May, following his February journey to China. But now some officials are talking about the India‐Pakistan crisis as casting a shadow over United States‐Soviet relations.

Mr. Nixon's thinking was outlined by Henry A. Kissinger, the President's adviser on national security affairs, in his briefing last week to newsmen on the India‐Pakistan situation. Mr. Kissinger was asked what impact the continuing Soviet support for India might have on United States relations with Russia. He answered:

Policy of Restraint

“We believe that the basis of a peaceful evolution with the Soviet Union requires that both, countries exercise great restraint in the many crisis areas around the world and that they both subordinate short‐term advantages to the long‐term interests of peace.

“We certainly are making great effort. We may not always succeed, but we are making an effort to approach problems everywhere, including in South Asia, with this attitude.

“The attempt to achieve unilateral advantage sooner or later will lead to an escalation of tensions, which must jeopardize the prospects of relaxation. We hope that the Soviet Union will use its undoubted influence to approach problems in the subcontinent in the same spirit and not to jeopardize the very hopeful evolution that has started by a short‐term approach. But we are still waiting to see. We have no judgment yet.”

Reliable sources said that Mr. Nixon made many of those same points in his letter to Premier Aleksei N. Kosygin last month urging restraint in the India‐Pakistan crisis. And Ambassador Jacob D. Beam reportedly reiterated them to Foreign Minister Andrei A. Gromyko recently.

The Soviet response, both public and private, has been consistent, officials said. The Russians have charged Pakistan with being responsible for the war by her repression of the East Pakistanis. Moscow has, asked for a cease‐fire and a simultaneous movement by West Pakistan to give autonomy to East Pakistan.

So far, the Russians have directed their fire primarily at the Chinese, who have been Pakistan's principal supporters at the United Nations. Soviet commentary has underscored, however, that the United States and China have voted together against the Russians on the various resolutions. Comments in the Soviet press have called the American stand “one‐sided” in favor of Pakistan and not solving “the fundamental cause” of the war — the repression of East Pakistan by West Pakistan authorities, and the subsequent flow of some nine million Bengal refugees to India.

One State Department official said the differences between the United States and the Soviet Union over India and Pakistan are comparable with their differences over the Middle Eastern situation.

He said that, in both areas, the Russians and Americans want to avoid a war and preserve the peace, but on crucial political issues, Moscow backs its “clients” — Egypt and India —and the United States refuses to push Israel and Pakistan beyond a certain point.

In the India‐Pakistan war, the United States is seeking a Security Council resolution that will give teeth to a General Assembly resolution last week calling for a cease‐fire and a withdrawal of Indian forces from Pakistan and Pakistani forces from Indian territory.