Secretary of State George P. Shultz ended four days of Middle East diplomacy today with intensive discussions of a unilateral Israeli pullback of its troops in Lebanon to more defensible positions, but with no progress in sight toward a full withdrawal of foreign forces.

"I wish I could report that somehow we see progress in the direction of simultaneous Syrian and Israeli withdrawal as we wish to see, but I can't give any such report," Shultz said in summing up his discussions.

He took heart, however, in finding general support in the region for the ultimate objective of a strong, independent and unoccupied Lebanon despite the seeming stalemate about how to achieve it.

Shultz also went out of his way to discourage any idea that U.S. Marines of the multinational force in Lebanon might fill the vacuum left by the departing Israelis.

He noted that the multinational troops had been organized to work in essentially "nonhostile" situations and said he would find it difficult to explain a more dangerous mission to Congress. Earlier, there had been plans for U.S. Marines to assist Lebanese soldiers in manning checkpoints on the Beirut-to-Damascus highway, but the Marines have remained in the Beirut area.

The most difficult immediate question, that of a planned Israeli "redeployment" of its troops within Lebanon, was the focus of nearly three hours of discussion in Jerusalem this morning between Shultz and top Israeli officials, including Prime Minister Menachem Begin.

The Israelis presented their case for a redeployment of their forces to positions they could hold indefinitely. Shultz refused to say publicly whether the United States approves or opposes such a redeployment and apparently gave no clear signal even in private of the U.S. reaction.

Shortly after Shultz left Jerusalem, however, a senior Israeli official asserted that the United States had committed itself to standing by Israel "diplomatically and publicly" in its plan for a partial withdrawal of its troops from Lebanon, Washington Post correspondent David B. Ottaway reported.

The official said the United States had committed itself to support Israel in the event of a Syrian refusal to withdraw its troops from Lebanon in a secret side letter Shultz and Israeli Foreign Minister Yitzhak Shamir signed at the time of the signing of the American-brokered accord on May 17.

Shultz, reached later in Cairo, denied that a partial Israeli pullback was mentioned in any side letter.

The letter, the text of which has never been made public, also excused Israel from going ahead with a total withdrawal from Lebanon if Syria did not agree to a similar evacuation of its troops stationed there, according to the Israeli official.

The official, who could not be identified under the ground rules of the briefing, called on Washington to persuade the Beirut government that a less than total Israeli pullout should not jeopardize the implementation of the Israeli-Lebanese withdrawal agreement.

Lebanon was not a signatory of the side letter and has said it will not go ahead with the accord if Israel pulls back only partially.

Shultz's remarks to reporters as he flew out of Jerusalem suggested that his discussion with the Israelis centered on the practical consequences of an Israeli pullback for the areas that would be vacated.

There is strong concern in Lebanon that a renewal of warfare between Lebanese Druze and Christian elements could break out if the Israeli troops leave the Chouf Mountains south of Beirut, one of the main areas that may be vacated.

It was unclear how fast or how far the Israelis intend to go in repositioning their forces. Shultz said Begin told him today that no final decision has been made.

A senior Israeli Foreign Ministry official, who could not be named, gave his country's view of a short-lived U.S. initiative that recently gave rise to Washington leaks and State Department denials. What happened, according to the Israeli's account, is that "vague ideas" were put forward by U.S. officials in Jerusalem that "maybe it would be a good thing if Israel would withdraw to the international frontier" of Lebanon without a corresponding Syrian withdrawal, in hopes that this would encourage a Syrian pullout.

"We shot it down," the Israeli official said of the U.S. "idea."

Despite Shultz's low-key approach and his efforts to depict his objectives as limited, his trip through the area, scheduled at the last minute, gave rise to expectations that he was carrying a program or powers that could break the stalemate over the withdrawal of foreign forces from Lebanon.

Shultz's mission to the Middle East two months ago resulted in the Israeli-Lebanese accord that was to be the first step toward full withdrawal, but Israel linked its pullout to a parallel pullout by Syria, a linkage Washington accepted. When Syria balked, the withdrawal process was stalemated.

Shultz was unable in talks in Damascus yesterday to persuade Syria to move under existing circumstances.

Following his meetings in Jerusalem, Shultz flew to Amman, Jordan, to brief King Hussein on his discussions in the other capitals, and then flew to Cairo for a meeting with Egyptian President Hosni Mubarak before returning to Washington.

Shultz's Middle East discussions capped a 15-day trip that began in the Philippines, included other stops in Southeast Asia, and then went on to India and Pakistan.

Ottaway reported from Jerusalem:

The senior Israeli official who briefed reporters said Shultz had held "friendly, intensive talks" with Begin and other top Israeli ministers and he insisted that Shultz had not asked Israel to delay its plan for a partial withdrawal from Lebanon.

The Israeli official said there was "full agreement" between Israel and the United States that "we have to stick to the May 17 agreement" and that "our ultimate goal is a simultaneous total withdrawal from Lebanon" of all foreign forces.

The annex to the May 17 accord states that "within eight to 12 weeks of the entry into force of the present agreement, all Israeli forces will have been withdrawn from Lebanon."

Israel in effect now wants to make only an initial partial withdrawal with no commitment to a timetable for total one that would remain contingent on the United States getting Syria to agree to a similar move.

The Israeli official said Syria's rejection of the Lebanese-Israeli accord had created a new situation requiring "other transitional alternatives" to its terms so that, if necessary, Israel could hold on "militarily and strategically" for a long time in Lebanon.

Asked if this did not require a renegotiation of the accord, he replied, "Categorically no. This treaty is not to be reopened by us or anybody."

Israel contends that a partial withdrawal, probably to the Awwali River just north of Sidon, will improve its situation by shortening supply lines, reducing casualties and lessening the pressure at home for a total, unilateral pullout.