Israel's cabinet today accepted "in principle" a U.S.-proposed peacekeeping plan for the Sinai, but instructed Foreign Minister Moshe Dayan to submit several amendments to the White House before flnal approval is given.

Cabinet officials denied there are still any major obstacles to implementing the peacekeeping proposal, and the government sought to minimize the importance of the amendments Dayan will suggest to Washington.

It was understood, however, that Israel will demand a binding written commitment by the United States to establish a multinational peace-supervising force when the Israeli Army withdrawal from the Sinai is completed. This, presumably, would satisfy the objections of some ministers who feel the U.S. promise on the multinational force is too vague.

The Cabinet last week put off approval of the peace-monitoring plan after several ministers argued that the Washington agreement had relieved the United States of a commitment to establish a multinational force in the Sinai.

However, Dayan is understood to have reminded the ministers that he told Secretary of State Cyrus Vance that if no international force is deployed in the Sinai by April 1982, the Israeli Army would not complete its withdrawal from the peninsula, captured during the 1967 Six Day War.

The Sinai peacekeeping plan, which has already been approved by Egypt, calls for joint Egyptian-Israeli patrols in a corridor three miles wide running from A1 Arish in the north to Ras Muhammad in the South. The Israeli forces will withdraw behind this corridor by the first of next year.

The United States, in addition to providing aerial surveillance, has agreed to increase to 200 persons its strength in the Sinai field mission maintaining an electronic-monitoring network and link the network to the U.N. Truce Supervising Organization, which is already deployed in the desert. The Sinai field mission was originally set up during the disengagement of Israeli and Egyptian forces following the 1973 Yom Kippur War.

As the Israeli Army moves east according to the peace treaty timetable, the buffer zone between it and the closest Egyptian troops will be supervised by Israeli-Egyptian patrols, with U.S. monitors joining the inspection tours and the United States providing logistic support.