Special U.S. envoy Robert Strauss said today he has found "very serious questions and reservations" in Egypt and Israel about an American proposal for a new U.N. resolution on the Middle East peace negotiations.

"I shall faithfully report these questions and reservations to the president and the secretary of state," Strauss said after a two-hour meeting here with Prime Minister Menachem Begin.

Earlier today the Israeli Cabinet rejected the U.S. proposal.

Begin strongly suggested that he expects the Carter administration to go back on its announced intention to propose the new Security Council resolution, designed to draw Palestinians into the West Bank and Gaza autonomy talks among Israel, Egypt and the United States.

"I do believe that this difficulty will soon be removed as a result of reconsidering the problem by our American friends," he told reporters after the talks with Strauss.

Taken together, their remarks cast a negative pall on the U.S. initiative and raised questions about whether it might be abandoned. Israeli sourses said Begin is counting on Strauss to persuade President Carter to abandon the plan, and the U.S. envoy's aides went out of their way to put distance between Strauss and the new U.S. proposal.

Strauss received final instructions on the initiative in an envelope handed to him only after he boarded his U.S. Air Force plane for the three day trip to Israel and Egypt, sources in Strauss'party said. He opposed the idea when it was discussed earlier in Washington, they added, partly because he foresaw the vehement Israeli reaction.

Begin's Cabinet, which met for four hours earlier today, accused the United States of trying to renege on commitments to Israel under the Sinai withdrawal accord of 1975, the Camp David accords of last September and the Egyptian-Israeli peace treaty of March 26.

Henry Kissinger, then secretary of state, pledged as part of the 1975 accord that the United States would not recognize or negotiate with the Palestine Liberation Organization until it acknowledged Israel's right to exist. The Israeli Cabinet, reportedly with rare unanimity, apparently believes the U.S. resolution is a way to squeak out of that pledge in an effort to persuade the PLO to accord at least tacit approval for West Bank Palestinian participation in the autonomy talks.

In addition, Israeli officials say, Security Council Resolution 242, the basic U.N. framework for Middle East peace that would be modified by the U.S. proposal, is the basis on which the Camp David accords and the peace treaty were built. Altering 242 would bring into question the validity of these accords, they say, so much so that Israel would reconsider its obligations under them to participate in the autonomy talks

The Israeli opposition was well known. It had been voiced loudly even before Strauss officially conveyed the new U.S. policy proposal to Begin Friday. Egypt's unexpected lack of enthusiasm became clear only during Strauss' talks last night in Ismailia with President Anwar Sadat.

Strauss said the Egyptian leader expressed concern about any initiative that could distract Israelis and Egyptians from the autonomy talks as they are now organized. Despite slow progress, Sadat has said he is satisfied with the pace of the talks and sees no need to get Palestinians involved at this stage.

Israeli, Egyptian and American working groups are negotiating this week in Alexandria, Egypt, on a set of reference points worked out in the last plenary session of the talks held two weeks ago in Haifa, Israel.

But the United States apparently has concluded that a Security Council debate on the Palestinian issue scheduled next week in New York puts U.S. policy in such a harsh spotlight that some positive U.S. move is necessary to retain the confidence of such moderate Arab nations as Saudi Arabia and Jordan and to encourage Palestians outside the PLO to consider joining the talks. State Department officials are reluctant to be seen vetoing an Arab backed resolution being sponsored by Kuwait, and thus they had proposed offering the compromise resolution of their own.

This resolution, as they saw it, would stop short of Palestinian and Arab demands for endorsing a Palestinian state and the right of Palestinian refugees to return to what is now Israel. It would, however, make explicit reference to the rights of the Palestinian people and would mention the right to Palestinian self-determination.

This clashes sharply with Israel's concept of Palestinian autonomy. In Israeli eyes it would be limited to administrative functions, with Israel and its Army maintaining control of the territory.

But the compromise, as envisaged by State Department officials, would have fostered Arab confidence in U.S. intentions in the talks and, it was hoped, would have helped bring Jordanian and Palestinian participation.

With Egypt raising some reservations and Israel objecting strongly, however, Strauss was reported to feel that the proposal puts the United States in the awkward position of urging an unwelcome policy on both Egypt and Israel -- the two principals in the talks.

Strauss declared he had said nothing to Begin to justify confidence that he can persuade Carter to abandon the idea. It was clear from his comments, however, that he felt the initiative had encountered too negative a response in Egypt and Israel to produce any positive results in the talks.

He promised Begin that the strenuous Israeli objections would receive "very serious consideration as we go about our decision making process" in the coming days in Washington.

Some of Strauss' aides indicated they believed that he had been saddied unfairly with conveying an attempt at a new policy that was likely to fail. They underline his opposition to the idea from the beginning and suggested he carried out someone ele's decision because he was told to do so.