Israeli radio reported today that the government told the United States it had not violated its agreement on the use of U.S.-supplied cluster bombs because the weapons had been aimed only against military targets in the conflict in Lebanon.

The state-run radio, reporting on a message delivered Friday to Secretary of State George P. Shultz, said the government had justified its use of the deadly bombs on the basis that Syrian entry into the fighting had turned it into a "full-scale war."

"In these conditions," the radio quoted the Israeli explanation as saying, "it had been permissible for Israel to use the cluster bombs." They had been used "within the conditions laid down in the sale of U.S. arms," Israel reportedly told Shultz.

No detailed account of the Israeli reply other than that on Israeli radio was available here today, and it was unclear whether the radio was quoting directly from it.

But Israeli sources indicated that the radio's account of the letter was essentially correct.

"Israel used cluster bombs only for defensive purposes and against military targets only," one source in Jerusalem said in response to the radio report.

The use of cluster bombs is covered by provisions of the U.S. Arms Control Export Act of 1952 and by other, secret accords reached by Israel and the United States more recently. Those accords reportedly permit the use of cluster bombs only against "regular forces of a sovereign nation" and under "special wartime conditions."

The possible misuse of the weapons has opened a bitter debate in the United States, and the Reagan administration had requested an explanation from Israel about how the bombs had been used. On Thursday, the State Department delivered a confidential letter to Congress that reportedly said a "substantial violation" by Israel of the Arms Export Control Act "may have occurred."

Israel also was said to have expressed regret over the civilian casualties resulting from its use of the bombs. But it said they were the result of the "systematic deployment" of Syrian and Palestinian guerrilla forces in civilian areas, the radio said.

The Israeli newspaper Maariv gave an almost identical account of the Israeli reply to the American government. It said the Israelis had pointed to the scope of the war as a key rationale for the bomb's use, notably the entry of the Syrian Army into the fighting.

The use of the cluster bombs was expected to be discussed in today's Cabinet meeting, which issued no statement after a long session. The meeting reportedly was devoted primarily to a report on the state of the negotiations in Beirut on the withdrawal of the Palestinian guerrillas.

Sources close to the government said David Kimche, director general of the Foreign Ministry, reported to the Cabinet that no real progress had been made in the talks since last Sunday. He visited East Beirut Friday for talks with special U.S. envoy Philip C. Habib.

The government's assessment of the chances of the Palestinian guerrillas leaving West Beirut was now "very slim," the sources said.

They added that the Israelis also understood that the U.S. government had decided Habib's mission was very close to having reached a total impasse.

In an interview with Israeli radio today, Kimche said he hoped President Reagan, during a scheduled meeting with Saudi and Syrian foreign ministers Tuesday, would manage to persuade Syria to accept the guerrillas.

The issue of the use, and possible misuse, of U.S.-made cluster bombs by Israel in its invasion of southern Lebanon has not been aired here yet, and the government has said little about it publicly.

The Israelis are known to have used the lethal antipersonnel weapons--which explode above ground and spray hundreds of tiny, shrapnel-producing bomblets over an area about the size of a football field--in at least two areas.

One was in the mountainous Chouf region of south-central Lebanon near Ain Dara just south of the Beirut-to-Damascus highway, where Syrian forces successfully blocked the Israeli advance toward the vital road link for days.

The Israeli drive through the Chouf was not primarily aimed at the Palestinians but was part of a secondary objective of forcing Syrian forces--which have been in Lebanon since the civil war as peace-keeping units--out of Lebanon's eastern Bekaa Valley and indeed all of Lebanon. Hardly any Palestinian guerrillas were in the Chouf region.

Washington Post correspondent Jonathan C. Randal visited an Armenian sanatarium near Ain Dara that was hit by a cluster bomb during the Israeli drive through the area. The hospital was located just below the road where Syrian tanks and armor had blocked the advancing Israeli column.

The outer shell of several cluster bombs were visible along the road leading toward Ain Dara from the Damscus highway. Why the Israelis decided to use cluster bombs against the tanks dug in along the road was not clear, but they may have been aimed at the troops accompanying them.

The Israelis also used the cluster bombs in attacking the Palestinian camps in the southern outskirts of Beirut. In particular, Western correspondents visiting the camp of Burj Barajneh in the first weeks of the war were given some of the "bomblets" as souvenirs.

The Palestinian camps contain both civilians and guerrillas. As the war progressed, however, most of the civilians were evacuated from the camps and took shelter in the city's center.