Amid frenetic diplomacy initiated by the United States in an effort to end hostilities, Israel appeared intent tonight on buying time to consolidate its gains in Lebanon and to hasten the departure of Syrian and Palestinian forces there.

In deflecting a U.S. call for an immediate cease-fire coupled with an Israeli withdrawal, Prime Minister Menachem Begin's government is mindful that action by the United States and the Soviet Union, each with its own motives, has ended all four previous Middle East wars--and cut short Israel's military successes.

David Kimche, director general of the Foreign Ministry, said tonight on Israeli radio that Israel hoped to persuade others that the objective "to stamp out the scourge of terrorism . . . is so important, not only for us but for all countries that are being subjected to terrorism, that they will understand," but Israel's priorities seemed more internal and regional than international.

Israel Defense Force casualties, while not high for such a massive operation, are 52 reported killed and 356 wounded so far. In a small country, casualty figures can become an important factor in military considerations. It seems unlikely that Begin would agree lightly to a withdrawal with the main objective of the invasion still in question.

Moreover, and perhaps more importantly, a public consensus is clear: Israelis want the threat of cross-border terrorism removed. The government has convinced them that achieving that goal is close at hand.

To accede to international pressure to back away from that objective would be a severe domestic political setback for Begin. Furthermore, the operation is certain to become an enormous drain at a time when inflation and budget deficits are major problems.

Faced with these political realities, Begin has been showing the political dexterity that is his hallmark.

Today started for Begin at 2 a.m. with the delivery of a note understood to have contained a call by President Reagan for an immediate end to fighting and withdrawal of the Israeli invasion force that already has reached the edge of Beirut.

Begin, Israeli sources said, awakened his Cabinet ministers and obtained a consensus that Israel was prepared to agree to a cease-fire effective Friday morning, but not to a unilateral withdrawal without a negotiated settlement.

The message was transmitted in a 7 a.m. meeting with U.S. Ambassador to Israel Samuel W. Lewis. Begin then met with his Cabinet.

After that meeting, Cabinet Secretary Dan Merridor touched off a wave of optimism by describing Reagan's letter as having been written in a "friendly spirit," and adding that "the possibility was raised that Secretary Alexander M. Haig would visit Israel tomorrow."

One senior Foreign Ministry official denied that Reagan's message contained a request for Israel to withdraw from Lebanon after ceasing hostilities.

Begin also conferred with members of the parliament's opposition, including Labor Party leader Shimon Peres, former prime minister Yitzhak Rabin and former foreign minister Abba Eban.

Peres later told reporters, "It is up to the government to answer, but we are for a cease-fire."

In a clear show of support for Begin government decisions, Peres said, "We understand that the parameter of 40 kilometers [25 miles] remains the only target of the Israeli operation in Lebanon, namely to clear it of hostile guns and Katyusha rockets. I understand also there is no plan to take over Beirut or to conquer it."

Peres' assessment came after Israeli planes were reported to have dropped leaflets on Beirut urging the Syrian forces to leave because Israeli troops intended to capture it.

At noon, Lewis delivered a second message from Reagan. Although its contents have not been disclosed here, reports from Washington indicated that it said Begin's response to the U.S. call for a cease-fire and withdrawal was unsatisfactory.

Israeli sources said that Begin responded this time that Israel was not prepared to withdraw until it was assured that PLO guerrillas would not return and resume shelling settlements in northern Israel.

Begin's posture appeared to support the notion that pleasing the Reagan administration is not now among Begin's highest priorities.