Israeli Prime Minister Shimon Peres moved today to keep a high-level dialogue with Egyptian President Hosni Mubarak alive even as he rejected a key portion of Mubarak's initiative to start new Middle East peace talks.

Praising Mubarak's efforts as "by and large positive," Peres said in an interview that this week's intensive contacts between Egyptian and Israeli officials have produced "an opening" for improving bilateral relations and have turned "an icy situation into a dialogue situation."

He pledged to work for "an honorable solution" to a continuing Egyptian-Israeli territorial dispute over the Gulf of Aqaba resort of Taba.

But, in comments that dispelled much of the confusion and conflicting assessments that have surrounded Mubarak's sudden initiative, Peres disclosed that he had told Egyptian envoys who came to Jerusalem that he cannot accept a Mubarak proposal for a three-stage negotiation that would begin with direct talks between the United States and a joint Jordanian-Palestinian delegation.

"The problem is not to make peace between Jordan and the United States," but between Jordan and Israel, Peres said, adding that leaving Israel out of such talks would amount to a new attempt by the Arab side to "convince Washington to commit the United States on behalf of Israel and twist Israel's arm . . . . I said no to this."

Peres repeated his interest in opening direct negotiations with Jordan now. Mubarak's proposal also centers on the formation of a joint Jordanian-Palestinian delegation that would include supporters of the Palestine Liberation Organization.

But both leaders suggested in separate interviews with The Washington Post this week that the real focus of the flurry of conversations has been Egyptian-Israeli relations, with the discussion about the joint Arab delegation serving largely as a vehicle to probe each other's flexibility.

Taken jointly, their comments suggest that Mubarak's initiative has become a two-track effort to improve relations with Israel and, if possible, to get the United States involved in a political dialogue with the PLO with Peres' blessing.

On Wednesday, Mubarak in Cairo described this step as essential to his strategy of moving on to include Israel in the talks with the joint Arab delegation in a second stage and finally convening an international conference to ratify the agreements reached.

This three-staged proposal, Peres indicated in his remarks, was the only one put to him directly by Mubarak's emissaries.

But, in another indication that the two leaders are seeking new opportunities to improve relations that have been effectively frozen since Israel's 1982 invasion of Lebanon, Peres said he decided to stress in his public response his agreement with reports published earlier in the week that said Mubarak was proposing direct Israeli-Jordanian talks with Palestinian participation.

"The idea of meeting straightforward with a Jordanian-Palestinian delegation, or a Jordanian delegation that included Palestinians -- but not PLO -- I gladly received it immediately," Peres said, specifying that he would agree to such a meeting in Cairo, hosted by Mubarak and attended by the United States, if Mubarak proposed this formally.

Peres praised the United States for joining him in rejecting the three-stage proposal: "Washington stood very firm." The American attitude, he said, had been expressed as, "You gentlemen go ahead and negotiate directly."

Peres joined Mubarak in saying that the stalled negotiations over the return of the four-acre strip of beach at Taba on the Gulf of Aqaba should be resolved fairly easily. But he avoided answering directly when asked if agreement had been reached this week on resuming the negotiations.

"If it were not for public opinion, perhaps the solution cold be very pragmatic, quite quickly . . . ," he said. "The mere fact that there is a more intensive dialogue gives us an opportunity. Instead of an icy situation, we now have a dialogue situation."

Both Mubarak and Peres cited the decision by the five-month coalition government headed by Peres to withdraw Israeli troops from Lebanon by this summer as having opened the way for the tentative rapprochement between their two countries, bound by an American-sponsored peace treaty since 1979.

Peres said Israeli troops in southern Lebanon would halt the retaliatory raids and other harsh measures imposed on Shiite Moslem villages if the Shiites would stop their attacks on Israeli troops preparing a new staged withdrawal. But he indicated that he did not expect such a truce would be reached.

"The Shiites misinterpreted our patience," Peres said. "You won't find an army in the world that will not protect the lives of its soldiers, and somehow the Shiites forgot this basic rule. The Army protects itself. As a matter of fact, we kept postponing the retaliation to give them a chance."

He insisted that the Israeli withdrawal plan will not be affected by the upsurge in Shiite attacks. "We are not going to change our minds simply because somebody is shooting mortars at us. This is a military timetable, not a political timetable."

Peres indicated that his government, in contrast to the Likud governments headed by Menachem Begin and Yitzhak Shamir, would not seek to influence political developments in Lebanon and would not put a high priority on seeking a withdrawal of Syrian troops from Lebanon to match the Israeli pullout.

Asked about demands by some Islamic groups that Lebanon be turned into a Shiite Islamic republic, Peres responded: "That is not an issue we can deal with. It is a great problem for the Arab world." On the Syrians, he predicted they would find that Lebanon "is not such a great gift to the Syrian strength."

Peres indicated that Israeli concern about the holding of Soviet-American talks on the Middle East in Vienna last month had been allayed by the failure of the talks to make any progress and by an apparent assurance from Washington that neither the Soviets nor the Americans were in favor of continuing the talks.

Peres spoke a few days before Israeli Finance Minister Yitzhak Modai is to depart for Washington for discussions on Israel's request for increased economic aid, including a proposed special appropriation of $800 million this year. The prime minister acknowledged that the economic austerity measures his government has taken have not completely satisfied Reagan administration demands for fundamental changes in the Israeli economy, but he indicated that the differences over this issue are not a major source of friction in U.S.-Israeli relations.

Calling the differences on economic issues "a very friendly argument," Peres said of the administration, "I do not doubt their friendliness. I argue about their professional approach, but not about their motives."

He said the United States has not given Israel a definite answer on the request for a supplemental appropriation of $800 million, nor has it outlined specific economic steps it expects to be taken here as a condition for the extra aid.

"We have neither a final yes or a final no," Peres said. "They say you must do a little more in general. They are careful not to intervene in our process, and we appreciate that."

Peres stressed the political aspects involved in attempting to reverse Israel's political decline and the necessity for his divided coalition government "to carry the people with us" in implementing painful austerity measures.

"We believe that the set of measures we are taking can yield better results than what is appreciated in the U.S."

The prime minister acknowledged past Israeli "mistakes" in managing the economy, but said the country's main economic problems stemmed from its heavy defense burden and the cost of repaying loans from the United States for the purchase of military equipment. However, in noting that Israel has always met its financial obligations "and would like to continue that," he appeared to rule out a request for a debt forgiveness program as a method to increase U.S. assistance to Israel.