The State Department, moving quickly to soothe the anger of Israel and its congressional supporters at the Carter administration's Middle East arms package, yesterday reaffirmed America's "lasting commitment" to Israel's security.

It took this conciliatory step as House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) warned that the administration faces a formidable hurdle in getting congressional approval for its decision, announced Tuesday, to sell advanced U.S. warplanes to Egypt, Saudi Arabia and Israel.

Congress can block the sales by a majority vote in both houses, and O'Neill said a move in the House to block the sale of F5E jets to Egypt and F15s to Saudi Arabia would produce a "very, very close" vote.

State Department sources said administration concern about congressional opposition helped prompt yesterday's statement defending the proposed sales. However, the statement was couched in language carefully crafted to reflect an upbeat tone about the "enduring and strong" nature of U.S.-Israeli relations.

The sources said the statement had been drafted "at the highest levels" and was intended to counter press speculation about the arms deal creating a new crisis in relations between Washington and Jerusalem.

The aim, the sources said, was to calm Israeli fears that the sales - greatly boosting U.S. military support of Egypt and Saudi Arabia, while giving Israel less than it wanted - would tip the Middle East military balance in favor of the Arab side.

O'Neill referred to these Israeli arguments when he said that members, of Congress from areas with large Jewish populations could be expected to oppose the deal. But, he added, Egyptian President Anwar Sadat's peace initiatives have greatly boosted his popularity in the United States and might give him substantial congressional backing.

O'Neill expressed concern that a debate on the issue could be "damaging" to the chances for Middle East peace and said he hoped the matter can somehow be kept out of Congress.

Also yesterday, Chairman Clarence D. Long (D-Md.) of the House Foreign Operation Subcommittee introduced a resolution urging Congress to reject the sale of warplanes to all three countries.

Calling the administration's proposal "short-sighted" and inconsistent with moves toward a Middle East peace settlement, Long said: "One day we could be watching Israelis, Egyptians and Saudi Arabians killing each other with American weapons."

The State Department unveiled its statement at its regular daily press briefing. When reporters asked about the announcement that Israeli Prime Minister Menachem Begin will visit Washington in March, a department spokesman, Kenneth L. Brown, said he said a statement "that would be appropriate to read at this time."

It said: "In general, we consider the ties between Israel and the United States to be enduring and strong. Clearly, Israel and we differ on some issues. Part of that relationship, as is always the case between close friends, is a frank airing of differences.

"But these differences do not in the least detract from our common search for peace and the last commitment of the United States to the security of Israel. We do not believe that the arms decisions announced yesterday (Tuesday) alter the basic military balance in the Middle East. Nor do they hamper the continuing efforts to reach an overall peace settlement.

"In our view, these decisions contribute to the legitimate security needs of the countries involved and give them the confidence to continue supporting the movement toward a negotiated settlement in the Middle East.

In elaborating on the statement, Brown said Begin was coming to Washington for "a quiet exchange held in the spirit of deep friendship" on the entire range of Middle East questions. He added:

"In our view, the visit is totally unrelated to the arms decisions. We don't consider this to be a crisis visit, and we don't consider that there is a crisis in U.S.-Israeli relations."

Asked specifically about Begin's angry reaction to the arms-transfer proposals, Brown said, "We are aware that the Israeli government was not happy with our decision . . . We hope that in the days ahead, as our consultations with Congress proceed, that the reservations being expressed about the decisions will be answered."