Prime Minister Menachem Begin today angrily defended Israel's approach to Middle East peace negotiations, and temporarily rejected Egyptian President Anwar Sadat's offer to resume military talks in Cairo this weekend.

Begin said he wanted to hear what Secretary of State Cyrus Vance has to say after he meets with Sadat in Cairo Friday - and what Sadat has to say in a scheduled speech to the Egyptian Parliament Saturday - before deciding whether to resume the Cairo sessions.

The Israeli prime minister emphasized, however, that he hoped Vance would be able to "convince President Sadat" that the Jerusalem peace talks which the Egyptian leader ordered broken off yesterday should be resumed.

"If the Egyptian government should at any day decide to renew or resume the talks, the government of Israel will be prepared to do so as well," Begin said in a speech to a visiting group of French Jews. "We hope the talks will be resumed. It is up to Egypt."

Officials in Jerusalem, however, were pessimistic that the political talks would be resumed in the near future. Some thought that political talks were dead, and that a new framework for negotiations would have to be found if the peace process is to continue.

Begin said today that he would "very willingly" go to Washington with President Sadat if invited to a tripartite meeting by President Carter. But both Begin and Vance expressed confidence in the present negotiating frame-work at a joint press conference.

In addressing a lunch for the visiting French group, Begin defended both his own actions and his peace plan in terms that were at times angry and uncompromising.

He said that five out of seven paragraphs of a joint declaration of principles had already been agreed upon - and that the remaining two were left for further negotiations - when Sadat suddenly recalled his delegation. Begin denied emphatically that he had bargained in bad faith, as claimed by the Egyptian press.

Begin disclosed that during his private talks with Sadat in Jerusalem in November, he told Sadat that if Israel were to give back sovereignty over the Sinai, Egypt would have to agree to a demilitarized buffer zone east of the strategic passes. Begin said that Sadat agreed to that, but when the idea was presented formally to the Egyptian delegation, they challenged it.

Begin also read from the minutes of his meeting with Sadat in Egypt on Christmas Day to prove that he had not misled the Egyptian president about Israel's intention to retain Jewish settlements in the Sinai, and protect then with the Israeli army. He spoke of how the settlers had made the desert bloom, and said: "We are not going to destroy the fruit of the labor of our men at the whim of the Egyptian government."

The "whim" of the Egyptian government is that Jewish settlements guarded by the Israeli army should not remain on Egyptian soil after a peace treaty has been signed.

Begin was equally uncompromising on the question of eventual self determination for the Palestinians in the West Bank and Gaza. He said that his own plan for self-rule gave them more independence that they had ever enjoyed under previous regimes, but he insisted that "security and public order Israeli authorities."

To the Arabs, this means a perpetual continuation on the Israeli occupation. The Americans had hoped to bring about a compromise in which Begin's self-rule plan could be considered a temporary plan with self determination possible in the future. But Begin defended his objection to self-determination, saying it would mean that the Palestine Liberation Organization would take over the territories, which would then become a Russian base aimed at the destruction of Israel.

As for Sadat's sudden decision to break off the political talks. Begin said there was speculation that this had been done to force the United States to bring pressure on Israel. Begin said he showed his peace plan to President Carter and other important American officials last month and that they had described it as both flexible and a step forward.

"Can a notable contribution become otherwise in four weeks?" Begin asked. "Can a constructive approach become a negative approach in one month? Can a great deal of flexibility turn into inflexibility? Can a long step forward turn into a long step backwards all in a few weeks? It is absolutely inconceivable . . ."

The Prime Minister defended his tough dinner speech of two days ago which so offended the Egyptian Foreign Minister, Mohammed Kamel. Begin bitterly criticized the Egyptian for having landed at Ben Gurion airport and immediately saying that peace was impossible unless Israel gave up East Jerusalem

Although the Egyptian foreign minister's remark differed only slightly from what Sadat had said in Jerusalem, Begin called the foreign minister's remarks "the most preposterous statement ever made by a guest." Begin said that "in classical French, it means chutzpah. " It was not only "our right but our duty to answer that statement as I did," he added. What's more, Begin said he would do it again.

Begin also fiercely attacked the notion that Israel should make concessions since Egypt had recognized Israel's right to exist.

"We never asked your president or your government or any other president or general to recognize our right to exist . . . ," He said.

Sadat offered not just recognition of Israel's right to exist, but Egyptian acceptance of Israel as a legitimate neighbor in the Middle East - something all Isralei governments have been seeking for 30 years.

Trying to assess today what had gone wrong, Israeli officials noted that the Egyptian press has been something less than friendly the past weeks in sharp contrast to the "soft line of the first month of the honeymoon."

"Begin himself today complained of having been called a shylock in the Egyptian press - "an old anti-semitic expression."

Foreign Minister Moshe Dayan, in a background session with Israeli reporters, said Sadat seemed to regard his insistence on total Israel withdrawal from occupied Arab territories as nonnegotiable, sources said. The world press had made it seem that Sadat was yielding point after point to the Israelis and this embarrassed him in the Arab world, Dayan said in his post mortem.

It was also probable, Dayan felt, that Sadat had expected more pressure on Israel from the Americans, and that the U.S. compromise proposals were not to his liking.

All of this could have avoided, in Dayan's view, if Sadat had thought more about a separate peace with Israel instead of always looking over his shoulder at the Arab world. It was unlikely, Dayan said, that political talks would soon be resumed. It would be difficult to reconstruct the same framework for negotiations, Dayan said, and a new framework will probably emerge.

Much of the burden of trying to put the Humpty-Dumpty talks back together again now lies with the Americans. Secretary of State Vance did not alter his schedule because of the Sadat decision and remained here today in Jerusalem. He spoke with Dayan and, after a game of tennis with U.S. Ambassador Samuel Lewis, he met with Begin to discuss the situation. Friday he flies to Cairo.

The impatience of Sadat with what he considers legalistic and evasive haggling is resented by the Israelis, who felt they were just getting down to really substantive issues when Sadat pulled the plug.

The two sides see the negotiating processes so differently that, in the view of one American, "Someone is going to have a jump to get into the conceptual world of the other" if true negotiations are to begin again.

That will not be easy. If Israeli public opinion today has anything in common with Syria and the Arab rejection front, it is the view that Sadat is at best capricious and unreliable.