Prime Minister Menachem Begin today indicated that Israel will delay any military intervention in central Lebanon in response to the installation of Syrian missiles while a special U.S. envoy travels to the Middle East in a last-ditch attempt to defuse the confrontation.

Philip Habib, a former assistant secretary of state, is expected to arrive here later this week to discuss with Israeli officials the Syrian deployment of SA2 and SA6 surface-to-air missiles last week in the strategic Bekaa Valley east of Beirut.

The missiles were deployed after Israeli warplanes shot down two Syrian helicopters that, according to Israeli sources, had been used in attacks on Christian forces in the mountains overlooking the Lebanese city of Zahle.

After meeting with senior Cabinet ministers, Begin said Israel is willing to explore all diplomatic avenues to resolve the crisis, although he stressed that efforts by the United States to convince the Syrians to withdraw the antiaircraft batteries have so far yielded no results.

"Only a miracle would influence the Syrians to remove their missiles in Lebanon," Begin told reporters after the Cabinet session.

The postponement of military action against the missiles came afer President Reagan, in a message to Begin yesterday, asked for more time to resolve the dispute through third party diplomatic mediation. There has been increasing pressure from the Israeli military establishment to attack the missiles in order to restore the Israeli Air Force's freedom of movement in Lebanese skies to conduct preemptive strikes against Palestinian guerrilla bases.

The SA2 missile, which the Soviets used in 1960 to shoot down the U2 surveillance plane from the United States, has an effective range of 24 to 30 miles, depending upon the altitude of the target. The SA6, which was used effectively by Egypt against Israeli aircraft in the 1973 Arab-Israeli war, has a high-altitude range of 36 miles and a low-altitude range of 18 miles.

Both could be uses against Israeli jets striking Palestinian guerrilla targets in central Lebanon, according to military officials. Moreover, the missiles are said to be equipped with homing devices that can deflect Israeli electronic countermeasures.

Begin sidestepped the question of whether an Israeli moratorium on air strikes in central Lebanon had been declared for the duration of Habib's visit, telling a reporter, "My friend, you can assume anything you like."

But senior government officials said no action would be taken while the Habib diplomatic mission is under way and until after it is clear that the Syrians have no intention of removing the missiles.

Begin called Habib a "wonderful and experienced diplomat," but said the United States has given no indication of what proposals the special envoy will bring to Israel.

The prime minister said there was "no grain of truth" to reports that Isreal had come under intense pressure from the Reagan administration to refrain military action. "There has not even been a sign of pressure," Begin said.

He called Reagan's message a "most friendly letter."

"We speak with the United States as friends and allies," he said.

The Israeli response to Reagan's message was to be delivered to the White House today by Israeli Ambassador Ephraim Evron.