Special presidential envoy Philip C. Habib will head back to the Middle East this week, possibly today, as the Reagan administration resumes efforts to avoid an Israeli-Syrian military conflict over the stationing of Syrian antiarcraft missiles in Lebanon.

Tensions in the lingering crisis subsided somewhat last week when Syria, responding to suggestions of a special Arab League committee, lifted its 91-day seige of the Christian town of Zable in central Lebanon. That agreement has prompted hope that further progress can be made in the missile dispute, which is an outgrowth of the continuing battle between Israeli backed Christian Phalangists in Lebanon and the Syrian-backed Moselm forces in that war-torn coutnry.

Syria, however, still has several batteries of Soviet-built SAM missiles in Lebanon that were brought there after Israeli warplanes shot down two Syrian helicopters over Lebanese territory late in April. And Israeli Prime Minister Menachim Begin continues to demand that those missiles be withdrawn and to insist that Israel cannot wait "indefintely" before taking military action to wipe out the missile sites.

At the White House yesterday, President Reagan and his top foreign policy and White House advisors held a 90-minute luncheon meeting with Habib, whose previous efforts at shuttle diplomacy in the region have been praised by all sides as a factor in preventing a direct Israeli-Syrian clash, at least thus far.

In addition to the president and Habib, the meeting in the White House Blue Room also was attended by Vice President George Bush, Secretary of State Alexander M. Haig, senior White House aides Edwin Meese III, James A. Baker III, Michael K. Deaver and Richard V. Allen, and Assistant Secretary of State Nicholas A. Veliotes.

Deputy White House press secretary Larry Speakes told reporters later that the meeting was meant to allow Habib to give the president his views on the next step in the Middle East peace process. Habib, who prefers quiet diplomacy and tends to avoid contact with reporters, left the White House by a rear exit and both White House and State Department officials said they were under instructions not to discuss what new proposals or instructions Habib might be taking with him to the region.

Although there is some hope that a peaceful resolution of the missile impasse might open the way to resumption of wider Middle East peace efforts, senior White House officials said that the main thrust of Habib's mission remains the same: to continue buying time in the missile crisis.

"Every week that we can prevent a major military engagement is a plus and we hope, over a period of time, to make some progress," one top official said.

Habib first was sent to the Middle East on May 5, a few days after the Syran missiles were moved into Lebanon. He stayed for nearly three weeks, shuttling between capitals in Lebanon, Israel and Syria. He came back on May 29, winning praise from Reagan for his "miraculous" efforts to avoid war. He returned to the region on June 5, remaining until June 26, just before the Israeli election.

While arranging the truce around Zahle was accomplished primarily through the mediation efforts of Saudi Arabian and Kuwati ministers, the settlement also was viewed as a by product of Habibhs missions, including his efforts to get the Saudis involved in persuading both Lebanese sides to pull back.

Habib, the son of an immigrant Lebanese grocer, retired from the U.S. Foreign Service in 1979 after two heart attacks and a 30-year career that saw him rise to key Middle East positions under president Nixon and under secretary of state under president Carter.

Because Habib, now recalled to duty by Reagan, so far has helped avoid a military clash over the missiles and is held in esteem in many places, some State Department officials speculate privately that he eventually might be named as the president's special negotiator for the stalled Arab Israeli peace talks, including the negotiations on Palestinian autonomy called for in the Camp David agreements signed by Egypt and Israel.

White House and senior State Department officials, however, say there has been no talk of such an appointment, nor any proposal along those lines.