The officials in Jerusalem said that the main reason for the arms sales was to retain some pro-Western connection with Iran at a time when the United States and other Western countries were unwilling or unable to do so. Israel and Israeli intelligence had a close relationship with the Government of Shah Mohammed Riza Pahlevi, and Israel was generally considered to have the best intelligence on Iran. All of this was put into reverse, and the Israeli intelligence operation was decimated, by the Iranian revolution.

Western intelligence sources say the United States is carrying out a series of covert actions, including the financing of paramilitary forces of Iranian exiles operating in eastern Turkey, attempts to form a coalition of Iranian exiles and running a clandestine broadcasting station to report on the shortcomings of the Teheran Government. These sources said that the activities were aimed at blunting the Soviet Union's increasing ties to Iran and gaining some influence on the future course of events in that country.

They also held that Moscow was controlling agents who had succeeded in penetrating the high councils of the Iranian Government and the ruling Islamic Revolutionary Party. Other Israeli Objectives Seen

Reagan Administration officials and Western intelligence sources contend that whatever positive effects Israeli arms supplies to Iran might be achieving for the West, the Israelis had other objectives in mind. One is to weaken the Iraqi Government and army by keeping Iranian armed forces in the field and fighting. A second motivation is the hope that Iran might want the arms enough to refrain from endangering the lives of some 50,000 Iranian Jews, according to the State Department.

The arms supplied to Iran by Libya, Syria and North Korea are largely of Soviet origin and, according to Western intelligence sources, they are making Iranian ground forces dependent on Soviet rather than Western military equipment. What remains of the Iranian air force is still wholly dependent on American equipment.

The Shah had already begun to diversify his suppliers by buying over $1 billion in arms from the Soviet Union, and he had factories built to produce spare parts and ammunition for these arms. The arms bought from Moscow and now reportedly supplied by Soviet allies include Katyusha rocket artillery, surface-to-air missiles, antiaircraft guns, armored personnel carriers, small arms and antitank missiles. By 1978, the Shah's Government was operating a factory to produce the RPG-7 antitank missile, and this factory is still functioning. Iran Thought to Pay With Oil

Western intelligence sources could not put an exact dollar total on these supplies, but estimated the amount at several hundred million dollars. They assume that Iran is paying with oil.