Secretary of State George P. Shultz was told today that a unilateral pullback of Israeli troops in Lebanon, now under strong consideration in Jerusalem, would make a dead letter of the Israeli-Lebanese pact he negotiated during his shuttle mission to the Middle East two months ago.

This warning from Lebanese government authorities in Beirut was only one of a host of misgivings, complaints and objections presented to Shultz about the contents and implementation of the May agreement, which the secretary of state is seeking to advance on his current trip.

In Jerusalem, a senior Israeli official said Israel is committed to pulling its troops south from the Beirut area to southern Lebanon and he proposed that this be done within the framework of the Israeli-Lebanese withdrawal agreement despite Syria's rejection of it. Lebanon strongly opposes any unilateral partial withdrawal by Israel. Details on Page A17.

Shultz said he has no intention of seeking to renegotiate the increasingly troubled pact, and at every stop in a long day he searched for ways to restore the momentum toward the withdrawal of foreign forces from Lebanon.

Nevertheless, Shultz's road to Damascus proved to be replete with new hazards and barriers to his efforts, and here in the Syrian capital he faces open hostility and reluctance to withdraw Syrian troops from Lebanon in any fashion that would validate the agreement between Israel and Lebanon.

In a predawn conference this morning, Shultz heard from Saudi King Fahd, America's most influential friend in the Arab world, a remarkably negative viewpoint on the Israeli-Lebanese pact. According to authoritative Saudi sources, the oil kingdom increasingly sees the agreement as a reward to Israel for its invasion and occupation of Lebanon and another element in an array of "separate peace" agreements that will make it possible for the Jewish state to retain control over the West Bank and Gaza Strip.

From the attitudes expressed to American visitors, it was evident that the Saudis are not inclined to press Syria to withdraw its forces from Lebanon in parallel with the Israeli-Lebanese accord as Shultz had hoped they would.

Earlier this year, Saudi sources said, Saudi Arabia responded to U.S. requests by helping to persuade Syria to agree to withdraw its forces unconditionally from Lebanon if Israel would do the same, and to do so simultaneously with such an Israeli pullout. This was before Shultz negotiated the Israeli-Lebanese pact, which contained security provisions objectionable to Syrian President Hafez Assad and measures of political and economic normalization that both Assad and the Saudis oppose.

Saudi officials said the opposition to the normalization aspects of the Israeli-Lebanese pact is broadly shared within the Arab world. In a brief exchange with reporters as he said goodbye to Shultz this morning at Jeddah Airport, the Saudi foreign minister, Prince Saud, called on Israel to withdraw from Lebanon, saying that "we don't equate" Israeli forces there with the Syrian troops that originally had been invited in by the Lebanese government.

Saud also told reporters that "partial withdrawal inherently means they the Israelis will keep a piece of Lebanon."

A similar but more pointed plea for a full Israeli withdrawal is reported to have been made to Shultz in closed meetings.

On leaving Saudi Arabia, Shultz said it was "most gratifying" to learn from Fahd that his country and the United States continue to share "the objectives" of removal of all foreign forces from Lebanon and reemergence of national authority within that country.

Shultz has made only the most general statements about a partial pullback on the part of Israel, taking the position that any such withdrawal should be arranged in a way that contributes to the total pullout of foreign forces that the United States in seeking.

In Beirut, his next stop, Shultz found a Lebanese government gravely concerned about the possibility of a unilateral Israeli redeployment--a pullback from the southern and eastern suburbs of Beirut, where Israel's forces repeatedly have come under attack--to more defendable lines in southern Lebanon.

The fear in Beirut is that this would set the stage for a permanent de facto partition of the country, with Israel holding sway over a large part of southern Lebanon and Syria remaining in control in the Bekaa Valley and other areas it finds convenient to dominate.

Although the Lebanese government has signed the pact with Israel and the Lebanese legislature has ratified it, the two countries have not exchanged the instruments of ratification. A senior Lebanese official told reporters this legally essential step will not be taken until Lebanon is fully satisfied that the agreement will be completely implemented--that is, that Israel will withdraw completely from Lebanon.

The official said Lebanon strongly opposes any partial Israeli withdrawal that is not clearly and explicitly a step in an established program of total Israeli pullout. Should Israel go ahead despite this objection, the official said, Lebanon will consider itself under no obligation to implement the normalization provisions of the pact, leaving it, in effect, abandoned.

This position, U.S. officials said, was given Shultz by Lebanese officials and presumably will be passed along by him to authorities in Jerusalem when he reaches Israel Wednesday afternoon.

Lebanese Foreign Minister Elie Salem, saying goodbye to Shultz in front of reporters, said, "We are reassured by the American commitment, which has not wavered," to bring about withdrawal of foreign forces from his country. "We have walked with the United States in this difficult path," Salem said. "We hope it will lead to total withdrawal" of foreign forces.

After about four hours in Beirut, Shultz flew here this afternoon. He was met at the airport by Syrian Foreign Minister Abdul Halim Khaddam.

U.S. officials said Shultz would meet with Khaddam and President Hafez Assad on Wednesday.