Defense Minister Ezer Weizman yesterday joined the chorus of Israeli leaders criticizing the proposed U.S. sale of warplanes to Egypt and Saudi Arabia as a setback to chances for peace.

"In the last three months, the Egyptians made serious mistakes in their conduct of the peace negotiations; we may also have made some mistakes, but the recent arms deal is the American contribution to this series of mistakes," Weizman said during an interview on Israeli television.

The Israeli denfense minister said, however, that he was not surprised by the U.S. decision.

"In Egypt today, the Russians are out and the Americans are in. In the Middle East it is customary for whoever comes in to come mounted either on a tank or a plane," Weizman said.

Weizman's warning of a threat to the peace process followed a theme struck by Prime Minister Menachem Begin and Foreign Minister Moshe Dayan. The defense minister expressed optimism, nevertheless, that the negotiations would succeed.

The Carter administration has proposed that lsrael receive 70 F16 interceptors and 15 of the advanced F15 fighter-bomer, while Egypt would receive 50 of the less-sophisticated F5E.

Saudi Arabia, however, is to receive 60 of the F15s.

While Begin and Dayan have immediately raised the specter of a security threat to Israel, Weizman, who served as a commander of Israel's air force for a number of years, refused to predict the security impact of the proposed sale. He said the question is still under careful study.

Weizman revealed, meanwhile, that the israeli government is preparing for a major review of its entire policy toward new settlements in the Sinai and on the West Bank, one of the key sticking points in the negotiations with Egypt. It was reported earlier this week that Weizman recently ordered a halt to work on outposts deep in the Sinai.

Dayan, who arrived back in Israel yesterday from talks in the United States, said that Assistant Secretary of State Alfred Atherton's return to the region will signal the start of a new stage in the negotiating process, including a possible resumption of the Israeli-Egyptian military talks in Cairo.

Atherton is expected to arrive here Monday Night, coming first to Israeli instead of to Egypt as apparently had been originally planned.

The resumption of Atherton's shuttle diplomacy will coincide with a visit to Washington by Egyptian War Minister Mohammed Abdel Gamassi and a visit to Cairo by a U.S. military mission, apparently to discuss arms sales.

News agencies reported these other developments:

The Soviet Communist Party newspaper, Pravda said the U.S. decision to sell planes to Egypt, Saudi Arabia and Israel represents a fresh spiral of the arms face in the Middle East and is an obstacle to peace.

The paper said the proposed sale to Israel gives it more power to resist a settlement.

Supplying Egypt and Saudi Arabia with warplanes, Pravda said, would widen the division in the Arab world and tie "rightwing Arab regimes" to Washington.

The paper also said the proposed sales mean that President Carter is going back on his pledge to curb U.S. arms sales abroad.

Former Israeli Prime Minister Yitzhak Rabin has accused Prime Minister Begin of a "childish" approach to foreign policy and of misinterpreting U.S. views on the Middle East.

"The government has undermined its credibility," Rabin said in a speech to his Labor Party.

"Begin doesn't understand that when the Americans say his peace plan is a fair basis for negotiation, they mean: you took the right step, but now you have to do more," Rabin said.

Mocing the Polish-born Begin's manners, Rabin said: "The old concepts of Polish honor do not apply in a diplomatic give-and-take."

Rabin also accused the government of setting up Jewish settlements in occupied Arab land "in disguise" by attaching them to military bases or labeling them "archeological expeditions."