Presidential emissary Philip C. Habib will return to the Middle East shortly after Thanksgiving to deal with rising Arab-Israeli tensions over Lebanon, the State Department announced yesterday.

The announcement did not portray the resumption of Habib's missions as an emergency effort, but the volunteered declaration that "tensions have been rising lately" reflected U.S. apprehension about trends and attitudes on both sides of the Lebanese-Israeli border.

Israeli military officials have expressed increasing concern about what they charge is a buildup of Palestine Liberation Organization weaponry in Southern Lebanon since Habib arranged a cease-fire in the area last July.

U.S. officials are reported to have some evidence of such a buildup, but there is no U.S.-Israeli consensus about its seriousness.

Among Habib's objectives, sources said, will be the pullback of threatening weaponry on both sides of the Lebanese-Israeli border.

Adding to recent tensions was a confrontation in the last week involving PLO guerrillas, the Southern Lebanon militia of Israel's ally, Maj. Saad Haddad, and U.N. peace-keeping forces in the area.

The conflict was defused after international pressures were brought to bear, but there was no solution to the underlying problem.

A renewed Israeli military attack into Lebanon or some other resumption of armed conflict, in the U.S. view, not only could destroy the tenuous truce but also could derail broader peace efforts in the area.

These include the Camp David process scheduled to restore Israeli-occupied Sinai territory to Egypt next April.

State Department spokesman Dean Fischer, announcing the resumption of the Habib mission, said the retired diplomat's travels will be "essentially open-ended."

Fischer declined to announce a departure date or schedule but said Habib is expected to revisit Israel, Lebanon, Saudi Arabia and Syria, principal stops in his earlier round of negotiations.

The critical importance of Saudi Arabia, instrumental in arranging the July cease-fire, was underlined by the decision to await the results of next week's Arab summit in Fez, Morocco, before sending Habib back to the Mideast.

The Saudis have been engaged in a nearly constant round of inter-Arab diplomacy in an effort to gain a maximum degree of Arab approval for Crown Prince Fahd's eight-point plan for an Arab-Israeli settlement.

Comments by President Reagan Thursday to a group of American Jewish leaders at the White House appeared to contradict the first point of the Fahd plan, the withdrawal by Israel from "all Arab territory occupied in 1967, including Arab Jerusalem."

The White House confirmed late Thursday that Reagan had told his visitors earlier in the day that "he preferred for Jerusalem to remain undivided under Israeli sovereignty."

At the same time, the White House and State Department issued statements saying the status of Jerusalem is to be determined through negotiations, statements that would seem at odds with the president's expressed preferences.

U.S. diplomats here and in Arab capitals sought to soften the impact of Reagan's statements on Jerusalem by declaring they represented "no change in U.S. policy."

The status of the historic city, which figures prominently in Islam as well as Judaism and Christianity, is a deeply emotional issue on all sides.

Another reported comment by Reagan to Jewish leaders appeared to add a new twist to U.S. positions on the PLO.

Reagan is unofficially reported to have said--and the State Department implicitly confirmed--that the United States will not deal with the PLO until the organization renounces terrorism and meets existing and longstanding U.S. conditions

Those are PLO recognition of Israel's right to exist and acceptance of U.N. resolutions 242 and 338 on Arab-Israeli peace.