Despite Prime Minister Menachem Begin's unequivocal assertion last week that the U.S.-Israeli strategic cooperation agreement was abrogated, Israel is showing tentative but unmistakable signs of willingness to reactivate the accord and smooth strained relations with its principal ally.

Although still unprepared to make the first open gesture toward resuming negotiations on the agreement, which was suspended by President Reagan following Israel's annexation of the Golan Heights, Israeli officials have been quick to pick up on conciliatory statements made in Washington and to match them with their own hints that strategic cooperation may not be as dead an issue as Begin said.

The strategic agreement, signed in Washington on Nov. 30, calls for U.S.-Israeli military cooperation to cope with encroachment in the Middle East by the Soviet Union. Specifically, it provides for joint naval and air exercises in the eastern Mediterranean Sea and the establishment of joint "readiness activities."

U.S. Sen. Charles Percy (R-Ill.), chairman of the Senate Foreign Relations Committee, just completed a three-day visit here, which is being portrayed by Begin's advisers as a step toward burying the hatchet over the Golan Heights issue and resuming the accord.

"It is a move toward eliminating misunderstandings of intentions," an Israeli official said of Percy's visit. "If there is a better atmosphere, other things could follow naturally."

Percy predicted a "new spirit, a new beginning" in U.S.-Israeli relations that would end the crisis brought on by the Golan Heights annexation.

A catalyst for this process, Israeli sources said, could be a visit to Israel by U.S. Secretary of State Alexander M. Haig Jr. According to reports from Washington in the Israeli press, such a visit may occur in February. The Foreign Ministry today said it had no confirmation of a Haig visit.

Just five days after Begin's unprecedentedly harsh rebuke of U.S. Ambassador Samuel W. Lewis for the suspension of the accord, the tone for a renewal of the U.S.-Israeli discussions on the agreement was set by Defense Minister Ariel Sharon.

In an interview Friday with the Hebrew daily Yediot Aharonot, Sharon said that while the United States had violated the strategic agreement by suspending it unilaterally, "The agreement, as a formal agreement, stands."

Since then, Israeli officials have taken pains to portray the strategic accord as not cancelled. This is in sharp contrast to Begin's admonition to Lewis that "I regard your announcement suspending the consultations on the memorandum as the abrogation of the memorandum."

Sharon emphasized in the interview that Reagan had said the agreement was not cancelled and that he hoped it would be carried out soon.

Taking that approach one step further, government officials in conversations this week have repeatedly drawn attention to the fourth article of the strategic agreement, which requires six months' notice if either side intends to terminate it.

But Israeli sources familiar with the intentions of Begin and his foreign minister, Yitzhak Shamir, stressed that the Reagan administration will have to make the first move.

"The prime minister said the United States cancelled the agreement. Now, the United States says the agreement isn't cancelled. It's up to the United States to prove it," one Israeli official, who asked not to be identified, said. He said one step the Reagan administration could take would be to reschedule talks on implementing the accord or make a move to appoint a joint coordinating council, as called for in the memorandum of understanding, to guide proposed working groups.

Israeli government sources stressed that it is unlikely that Begin will make any overtures to resume strategic talks until it is clear whether the United States will veto an attempt in the U.N. Security Council next week to impose sanctions on Israel because of the Golan Heights annexation. Officials said they were heartened, however, by a statement made Sunday by U.S. Ambassador to the United Nations Jeane J. Kirkpatrick, that U.S. support of sanctions is "inconceivable."

Meanwhile, upon leaving Israel today for Jordan, Percy said the "special" U.S.-Israeli relationship should not be jeopardized by "unilateral actions" by Israel, such as the Golan Heights annexation.

"In all my meetings, I stressed my deep concern about the current state of American-Israeli relations in the wake of recent events, especially since the enactment of the Golan Heights law," Percy said.

He added, "I have urged moderation of the rhetoric, which has aggravated the situation further. The special relationship between our peoples . . . should not be put at risk by unilateral Israeli actions taken without regard to the interests of the United States in strengthening regional security against external threats and advancing the peace process."