The United States began yesterday to establish the basis for coming negotiations on the future of Lebanon by linking Israeli withdrawal to the Jewish state's future security against cross-border attacks.

The statement by State Department spokesman Alan Romberg moved in the direction of Israel's insistence that it will withdraw from the newly occupied territory only when it is guaranteed a sanitized zone in southern Lebanon free of Palestinian fighters.

"We think the issue of not having Lebanon be a launching pad for attacks against Israel is linked to Israeli withdrawal," said Romberg. He made the statement when asked if the United States is pushing for an immediate Israeli withdrawal.

State Department officials were quick to describe the U.S. statement as simply a description of reality and a recognition that Israel's security concerns will be an essential factor in any settlement.

"It is a gross overstatement to say we have given Israel a blank check to stay put indefinitely," an official said. Some officials suggested that it is likely that there will be differences between the Reagan administration and the government of Prime Minister Menachem Begin in possibly drawn-out and difficult negotiations to establish the conditions for an Israeli withdrawal and the preservation of Lebanese sovereignty.

The announcement of the cease-fire in Lebanon was received with relief by President Reagan and Secretary of State Alexander M. Haig Jr., who were in their final day of European travel, and by officials in Washington. Haig said in Germany that the cease-fire was "a hopeful sign" but only "the first step" in restoring peace.

During the flight home, Haig told reporters there was "no way" for the United States to have obtained a cease-fire earlier, and he said Israel stopped its advance because it had realized its objectives.

"A nation doesn't resort to force and then simply stop under pressure from an ally," he said.

"We have a great deal of work to do," he continued. But he refused to be specific about possible ideas for a settlement and said it was "too early" to say if a sanitized zone will be established as Israel has demanded or whether U.S. troops will take part in a peacekeeping force to police such a zone.

Last night, the State Department issued a statement saying that "the essential first step--the cease-fire--is now being consolidated." It added:

"One thing is clear. A return to the previous conditions in Lebanon cannot be allowed. Conditions must be created that will permit the restoration of the full sovereignty, unity and territorial integrity of Lebanon on the one hand, and the protection of Israel's security on the other. Realism on all sides will be essential if our discussions are to achieve these goals."

Special U.S. envoy Philip C. Habib, who was in Jerusalem after a trip to the Syrian capital of Damascus, is expected to travel to Beirut shortly to begin exploring a new long-term arrangement for Lebanon.

An important element in the upcoming diplomatic manuevering will be Begin's scheduled June 21 visit here for talks with Reagan and Haig. There has been speculation that the unsettled Lebanese situation will force postponement of that trip, but both U.S. and Israeli officials insisted that, as of yesterday, they were proceeding on the assumption that Begin will come.

Egyptian Foreign Minister Kamal Hassan Ali is expected here this weekend to discuss with Haig on Monday his government's concerns that the Lebanon invasion will deal a setback to Egypt's campaign to reintegrate itself in the Arab world after being ostracized for making peace with Israel.

Haig almost certainly will try to gauge whether Egypt feels constrained by the Israeli action from pursuing what the United States had hoped would be a new, high-level attempt to achieve an Egyptian-Israeli accord on autonomy for the Palestinian inhabitants of the Israeli-occupied West Bank and Gaza Strip.

But, while Hassan Ali's visit is likely to mark the first step in a long series of diplomatic exchanges between the key actors in the Mideast situation, U.S. officials said that current administration plans call for Habib to carry the main burden in trying to bring about a solution.

A U.S. District Court judge here yesterday rejected a request by the Palestine Congress of North America that Haig be ordered to determine whether Israel had used U.S.-supplied arms in violation of American law and, if so, to notify Congress so that it can consider cutting off aid to Israel. Judge Aubrey Robinson said, "I have no intention of getting involved in the foreign policy of the United States."