Menachem Begin announced today he would make another attempt to form a "government of national unity" with the Labor alignment, the party that ruled Israel since independence but suffered defeat at the hands of Begin's Likud Party in the general election three weeks ago.

Although the Labor Party has turned down a similar request and is not expected to change its mind, Begin said he would make the offer again because of the "very grave problems" with which Israel is faced internally and externally.

Despite the differences between his party and the Labor Party, Begin said, "There are very serious national issues which unite all of us - resistance to the so-called Palestinian state in Judea and Samaria and the Gaza Strip, rejection of any withdrawal to the lines of June 1967, and unconditional rejection of any participation by the so called PLO in inter-state negotiations."

Although Begin did not mention the United States or its policies, his remarks followed Sunday's Cabinet debate, in which the outgoing Labor prime minister, Yitzhak Rabin, warned that President Carter's definition of a Palestinian homeland could "easily be interpreted as a consent to establish a new state for the Palestinians," something all the major Israel political parties oppose.

Outgoing Foreign Minister Yigal Allon said Sunday that "a grave argument might have developed" with the United States over the borders and the Palestinian issue even if the present government had won the election.

Begin made his remarks after a meeting with Israel's president, Ephraim Katzir, at which Katzir formally asked Begin to form the country's next government. Begin accepted and said that he hopes to form a government within three weeks.

Begin said he hopes to meet Labor's leader, Shimon Peres, Thursday for a "serious exchange of views" on forming a government of national unity.

His remarks were seen as an attempt to stress the points on which the majority of Israelis agree rather than on the more controversial planks of his party's platform, which say that the occupied territories on Jordon's west bank and in Gaza should never be surrendered even as part of a permanent peace treaty.

Meanwhile, negotiations between Begin's Likud Party and the Centrist Democratic Movement for Change continued today with the Democratic Movement continuing to seek assurances that it would play a major role in a coalition with Likud, especially in defense and security matters. Likud has 45 seats in Israel's 120-member Parliament to the Democratic Movement's 15.

Barring the extremely unlikely event of a national unity government, the movement is vital to Likud if it is to enjoy a comfortable majority.

Likud insiders warned today, however, that if the movement continues to drag its feet, Likud will be willing to form a narrow-based coalition with the National Religious Party and the small, ultra-religious party Agudat Yisrael, leaving certain Cabinet portfolios open if the Movement wants to join the government later. In the past when one labor-led coalition simply replaced another, there was no great necessity to hurry the transition period. Now that power is being transferred to another political party for the first time in Israel's history, Likud wants to press ahead.