Israeli government and opposition leaders united today in swift condemnation of yesterday's Soviet-American declaration on joint objectives for a full Arab-Israeli peace settlement.

As an atmosphere of extreme pessimism prevailed in official Jerusalem, Israel made it clear that it regards the declaration as a severe - possibly fatal - blow to the chances of successfully reopening meaningful peace negotiations with the Arabs.

The declaration, in the view of some leading Israelis, represents a departure from traditional American policy toward Israel, a possible abrogation of previous agreements and the strong possibility of an open confrontation between Israel and its one indispensable ally, the United States.

Foreign Minister Moshe Dayan reportedly tried hard to persuade the United States not to issue the joint communique.It was announced here that Dayan has been invited to discuss the situation with President Carter on Wednesday.

Finance Minister Simcha Erlich chaired today's regular Cabinet meeting in the place of Prime Minister Menahem Begin, who is ailing and still hospitalized. Erlich told reporters that the statement was "unacceptable" to Israel, represented a serious political development and that Israel might possibly have to prepare itself for a state of emergency.

Erlich said that the communique contained three implied elements to which Israel could never agree: The hint of an imposed solution, establishment of a Palestinian state and recognition of the Palestine Liberation Organization.

The joint declaration issued yesterday in New York calls for withdrawal of Israeli armed forces from territories occupied in the 1967 war: resolution of the Palestinian issue in a way that would assure "the legitimate rights of the Palestinian people;" establishment of demilitarized zones with U.N. peacekeeping forces, termination of the state of war and "establishment of normal peaceful relations." It also expressed a willingness by the United States and the Soviet Union to participate in possible international guarantees of new borders.

Former Prime Minister Yitzhak Rabin called the communique the most serious turn for the worse in Israel-American relationships since the 1967 Middle East war.

"It represents an American-Soviet agreement on the principles of a solution for the Arab-Israeli conflict and expresses for the first time the tendency to impose a solution to the conflict," Rabin said.

Former Foreign Minister Yigal Allon said the statement "may block the process of reconvening a peace conference."

The official government reaction, which was prepared yesterday at Prime Minister Begin's hospital bedside and released in the early hours before dawn today, made the following points:

The Soviet Union's demand that Israel withdraw to pre-June 1967 borders is "known to all" and contravenes the true meaning of Security Council Resolution 242.

The concept of a "peace treaty" is not mentioned despite the Israeli-American agreement of July 7, 1977 that the aim of a Geneva conference should be an overall peace settlement to be expressed in a peace treaty."

There is no reference at all in the statements to Resolutions 242 and 338 despite that the U.S. government has repeatedly affirmed heretofore that these resolutions constitute the sole basis for the convening of the Geneva conference."

The statement was ill-timed and could not but "further harden the positions of the Arab states."

Israel would continue to "aspire to free negotiations with it's neighbors."

In fact, the Soviet-American communique did not specifically call for Israeli withdrawal from all the occupied territories captured in the 1967 war, nor did it specifically mention the Palestine Liberation Organization (PLO). These omissions might conceivably be interpreted as compromises in Moscow's position, some observers said.

From Israeli's point of view however, it was unnecessary for the Americans to bring the Soviets back into the center of Middle East diplomacy after former Secretary of State Henry Kissinger had succeeded in nudging them aside.

Israel's main fear is that all her options and negotiation cards are being taken away in advance of negotiations and that the PLO is being brought into the negotiations despite Israel's strong objections.

Resolution 242 speaks of a refugee problem but not the "legitimate rights of the Palestinian people." Israelis point out, a phrase from the Soviet-American communique that particularly frightens Israel.

According to Israel's point of view, the phrase "Palestinian rights" is a great deal stronger than "Palestinian interests" to which pervious American administrations have referred. "It carries by implication the foundation of a palestinian state," a senior official said. "It suggests the beginning of a process that is bound to cause the destruction of Israel."

The the PLO was not directly referred to in the Soviet-American communique is immaterial because in Israel's view the reference to Palestinians is a euphemism for the PLO.

Almost as galling to the Israelis as the wording of the communique was the fact that the United States was a party to it in the first place.

In 1973 and in 1975, the United States committed itself in writing to consult fully with Israel on diplomatic moves vis a vis the Soviets and the Arabs and on all matters of who shall participate in a Geneva Conference, the Israelis say.

Israel was handed the text of the Soviet-American communique only 24 hours in advance of publication, according to informed sources, and was asked only for comment. This fell far short of "close consultations," in Israel's view.

Israel can now be expected to make a major effort to take its case to the American people and to world Jewry, political observers here say. Finance Minister Erlich, accroding to Isreal Radio, said that it is was important to stand up to outside pressure but that it depended on the people of Israel and on the support of "Jewish people throughout the world."