Israeli Prime Minister Menechem Begin appealed to American Jews and other Americans yesterday to supports his policies despite their rejection by the Carter administration.

"The unity of the Jewish community is the second defense line of the state Israel." Begin said, in an apparent effort to head off any split in the American Jewish community over his policies and the breakdown of peace negotiations in the Middle East.

"If we stand together," begin told an audience of American Jewish leaders at the Waldorf-Astoria Hotel, "we shall win the day." His speech to the Conference of Presidents of Major American Jewish Organizations was Begin's appearance before flying back to Israel.

Begin said that the head of the American Jewish group, Rabbi Alexander Schindler, told him when he presented his peace plan in December that 95 oercent of American Jews would support it.

It is still the only peace plan for the Middle East, Begin said. "Let us prove that 95 percent support it."

He called on American Jews to explain his plan to non-Jewish Americans, and promised them the aid of the Israeli diplomatic establishment in answering questions about his policies.

Begin described his talks in the White House Tuesday and Wednesday as difficult and he strongly rejected the allegation that Israel is an obstacle to peace. That accusation, he said, is "a moral wrong."

Schindler, who drew criticism from some American Jews recently when he attacked White House national security affairs adviser. Zbigniew Brzezinski for advocating policies he called unfair to Israel, gave an impassioned speech preceeing Begin in which he rejected the theary that American Jews should never publicly criticize their government.

"When we see our country selling out its idealism for petrodollars, we should say our country is selling out its ideals petrodollars," Schindler said.

"Whatever the evil we will call it by tis honest name," he said.

On a day when the White House seemed to feel it had to issue a denial of a Tel Aviv report that the Carter administration believed no progress toward peace is possible as long as Begin remains prime minister and also aware that Begin faces increasing opposition at home, Schindler asked American Jews to give Begin their full support.

"He is a worthly leader, not only of Israel, but of the entire Jewish people," Schindler said. He conceded that not every American Jew supports every detail of Begin's policies, but Schindler made an emotional appeal for American Jews to rally behind Begin.

Begin's speech was warmly applauded, but his reception was not as wildly enthusiastic as the one he received from a similar audience last July. At that time Begin, as he recalled yesterday, had just met Carter for the first time and in a spirt of amity, not confrontation.

Begin said of his meetings with Carter this week that there would be "no recriminations whatsoever."

He said that in Washington the peace plan he presented to Carter last December has disappeared "as though it was dropped into the Atlantic Ocean." Begin said that making his peace plan known to millions of Americans would be "the greatest help to Israel."

A major sticking point between Begin and the Carter administration is the Israeli proposal that the West Bank remain under military control while becoming locally autonomous. The Carter administration argues that Israel should give up most of the West Bank territory in a peace settlement.