A senior Pakistani official pressed his country's cautious position yesterday on Soviet withdrawal from Afghanistan, but a prominent House member suggested that Pakistan may be obstructing a Soviet pullout.

Zain Noorani, minister of state for foreign affairs, told Secretary of State George P. Shultz why Pakistan is refusing to sign a peace accord with the Soviet-backed Afghan government and is insisting on formation of an interim Afghan government instead. After meeting Shultz, Noorani told reporters the United States is "not averse to the idea" of an interim government, but he did not claim U.S. backing.

State Department sources said Shultz is sympathetic to Pakistan's position and does not believe it should be subjected to Soviet pressures to sign a quick agreement. However, the sources said Shultz is not taking a clear-cut U.S. position on the issue to his talks in Moscow Sunday and Monday with Soviet leader Mikhail Gorbachev and Foreign Minister Eduard Shevardnadze.

At a hearing on Afghan-related issues, however, Rep. Stephen J. Solarz (D-N.Y.), chairman of the House Foreign Affairs subcommittee on Asian and Pacific affairs, said Pakistan "has shifted its stance" on a peace accord "just as an agreement is at long last in sight."

Solarz said it is necessary to ask now "whether this new Pakistani position obstructs the possibility of a settlement" and whether it is in accord with U.S. interests in obtaining a Soviet pullout.

Gorbachev announced Feb. 8 that Moscow would begin withdrawing its troops from Afghanistan May 15 if an accord between Pakistan and the Afghan regime in Kabul can be signed by March 15. But Pakistani President Mohammed Zia ul-Haq said in a Washington Post interview in mid-January that he will not sign an agreement with the current Soviet-backed Afghan government.

State Department officials said the United States would like to see formation of an interim government in Afghanistan, acceptable to the Afghan resistance and to Pakistan, to oversee the withdrawal of Soviet forces. But there is skepticism whether this will be possible, especially in a short time.

Failing that, the officials said, there is likely to be increasing pressure on Pakistan to reverse its stand again and sign an accord with the Soviet-backed Kabul government. Pakistan might do this, according to the U.S. sources, if it calculates that the Kabul regime is nearly certain to collapse following the withdrawal of Soviet forces.

The pressures on Pakistan are already beginning to mount. U.S. officials said Soviet Deputy Foreign Minister Yuli Vorontsov, his government's diplomatic point man for Afghan negotiations, told Pakistani officials in Islamabad last week that they should "get on board the moving train" by approving an accord with the Afghan regime, or face international criticism for failing to cooperate.

Assistant Secretary of State Rozanne L. Ridgway, speaking on a USIA-sponsored telecast to Western Europe, said yesterday that Afghanistan is likely to be the most prominent of several regional issues discussed by Shultz with the Soviet leadership beginning this weekend.

Other regional questions prominent on Shultz's agenda are the Soviet position on U.N.-sponsored international sanctions against Iran, which are likely to be pushed in the Security Council by the United States in the next two weeks, and Shultz's emerging initiative on the Arab-Israeli peace process.

Shultz met Tuesday evening with about 25 House members and late yesterday with a similar Senate group to obtain congressional support for his Arab-Israeli negotiations, which will take him to the Middle East late next week after returning from Moscow. He also met yesterday with former Israeli foreign minister Abba Eban, who told reporters later that "Shultz appears encouraged by the support he's gotten so far for his proposals."

Another key item in the Moscow talks is to be the negotiations aimed at a treaty to slash U.S. and Soviet strategic nuclear forces by 50 percent. A State Department official who briefed reporters on plans for the trip yesterday said there was little likelihood of any major or immediate shift in the U.S. position on pending strategic arms issues.

The U.S. side hopes that the Moscow meeting, which is the first in a series planned in preparation for the next summit meeting of President Reagan and Gorbachev this May or June, will serve as "an energizing event" to produce progress in the strategic arms talks.

State Department spokesman Charles E. Redman said Shultz plans to meet in Moscow with noted Soviet dissident Andrei Sakharov to underscore U.S. support for the human rights movement.

Shultz also plans to meet with some human rights figures and persons awaiting emigration from the Soviet Union and to be interviewed by Ogonyok, a Soviet magazine that has taken a leading role in Gorbachev's glasnost, or openness, campaign.