Israel Foreign Minister Moshe Dayan departs for Washington today to resume a dialogue with Secretary of State Cyrus R. Vance that was broken off last month following the confrontation between Prime Minister Menachem Begin and President Carter.

During that encounter, it was Dayan who sought to find new language and new approaches in an effort to bridge the gap between Begin and Carter, and both sides were said to have felt that they were very close to arriving at a mutually acceptable formula for a declaration of principles that could guide further negotiations with Egypt.

But Begin, smarting under what he and his delegation considered to be roughshod treatment at the hands of Carter, sent his foreign minister back to Jerusalem before he left himself, believing that a cooling off period was necessary.

Besides taking up where he left off on a declaration of principles, the main purpose of Dayan's visit will be to find out "where we go from here," as one official put it.

In Israel's view, Egpyt has been slowly closing down the channels of direct Egyptian-Israeli contact one by one. After the open-door atmosphere that followed the November visit on Egyptian President Anwar Sadat to Jerusalem, Sadat first closed down the political talks in Jerusalem in January, and then the military talks in Cairo were suspended even though an Israeli delegation remains in Cairo waiting for a resumption.

Egypt refuses to resume direct talks until there is agreement on a declaration of principles, including Israeli recognition of Palestinian rights and Israeli withdrawal from occupied Arab territories.

Last month, Defense Minister Ezer Weizman visited Cairo for talks with Sadat and, in an interview with October Magazine, Sadat announced that Weizman would be returning to Cairo during the week of April 9, which has come and gone without an invitation to Weizman to return.

Israel sees a constant, if subtle, hardening of the Egyptian position since Sadat's visit here, and the fear is that Sadat may fall back into the pattern of talking only to American mediators and leaving it to the Americans to put pressure on Israel. That is why Weizman said last month that the shuttle diplomacy of U.S. special ambassador Alfred Atherton "may even have caused damage and delayed the peace process."

Dayan can be expected to try to persuade the American that his "redefinition" of Israel's stand on U.N. Resolution 242 (calling for Israeli withdrawal from occupied territories) should be enough to get negotiations going again. Wary to recent statements from officials in Begin's government that resolution 242 need not apply to Israeli withdrawal from the occupied West Bank of the Jordan River, the United States and Egypt have sought an Israeli commitment that it does call for territorial compromises "on all fronts," which is the position taken by previous Israeli governments.

In other Mideast developments, news agencies reported.

A land mine explosion killed a French soldier near the port city of Tyre, the second casulty since the U.N. peace keeping force moved into southern Lebanon a month ago.

Begin, addressing 3,000 cheering Jewish settlers at Kiryat Arba, in occupied Jordan, said Israel must be prepared to refuse to make territorial concessions on the West Bank. Referring to demands of withdrawal from the occupied territory, Begin, who is expected to discuss the issue next week with Carter, said, "We must be prepared with a strong heart to respond to such demands with one word. It's small, it's great and it's quiet - the word 'no',"

Meanwhile Atherton concluded three days of talks with Egyptian officials aimed at getting the peace talks back on the track, but said, "it is premature at this time" to discuss whether Israel has any new proposals for ending the deadlock.