The United States and Israel yesterday took a limited step toward "strategic cooperation" by approving their first formal agreement for combating military threats from the Soviet Union or its surrogates in the Middle East.

Called a memorandum of understanding on strategic cooperation, the agreement calls for joint naval and air exercises in the eastern Mediterranean but puts off other, more difficult questions, including how much American military equipment should be stored in Israel for emergency U.S. use.

"We're very pleased," one Pentagon official said of the agreement. Government sources said that Israel received far fewer commitments than it sought, at least for now.

Israel has suggested that weaponry for the U.S. Rapid Deployment Force be stockpiled in Israel where it could be rushed to troublespots in the Middle East and Africa. Israel also approached the Reagan administration about the possibility of receiving direct read-outs of information gathered by American spy satellites peering down on the Middle East and Africa from outer space.

Neither the one-page press release issued yesterday by the Pentagon nor the four-page text of the memorandum of understanding goes into such controversial specifics. Instead, the formal papers hammered out over the last several months speak in generalities.

The landmark agreement grew out of discussions between President Reagan and Israeli Prime Minister Menachem Begin last September. U.S. Defense Secretary Caspar W. Weinberger and his Israeli counterpart, Ariel Sharon, put the finishing touches on it yesterday.

As Sharon emerged from a luncheon with Weinberger at the Pentagon, he told reporters clustered in the hall: "It was what we sought." Weinberger and Sharon issued a joint press release at the Pentagon in which they said, "The agreement is designed to enable the two countries to act cooperatively, to provide each other military assistance to cope with threats to the security of the entire region caused by the U.S.S.R. or Soviet-controlled forces introduced from outside the region into the region."

The defense officials then quoted from a statement in the memorandum of understanding designed to assure Arab states that the United States and Israel had no intention of ganging up on them:

"The strategic cooperation is not directed at any state or group of states within the Middle East."

Under "broad purposes" the four-page agreement states that one purpose is "to provide each other with military assistance for operations of their forces in the area that may be required to cope with this threat." This would seem to leave the door open for Israel to provide at least temporary support for operations of the U.S. Rapid Deployment Force if it should go to the Middle East.

One administration official portrayed the agreement to conduct joint U.S.-Israeli naval and air exercises as highly significant in terms of making the Soviets think twice about stirring up trouble in the Middle East.

"The Israeli Air Force working with the U.S. Navy is no small thing," he said.

The prospect of the Israelis repairing and maintaining U.S. aircraft is also raised within the body of the memorandum. "Cooperation for the establishment of joint readiness activities, including access to maintenance facilities and other infrastructure" is the way the agreement expresses that possibility.

Joint U.S.-Israeli groups will work out the details of mutual military cooperation, ranging from exercises in the eastern Mediterranean to studies of how the Israeli defense industry could be made more competitive to qualify for U.S. defense contracts.

A coordinating council is scheduled to meet in January, according to the Pentagon. Also, Weinberger will visit Israel next year at the invitation of Sharon.