King Hussein of Jordan refused today to offer military help to neighboring Syria if it is attacked by Israel. He blamed the Israeli government, however, for worsening an already "disturbed, dangerous situation" through "intolerable" and "provocative" policies in Lebanon and the West Bank.

"Jordan already has its hands full on the longest confrontation line with Israel," Hussein declared in answer to a question whether his country would help Syria in thhe event of conflict with Israel.

Hussein thus became the only major Arab leader to refuse to offer aid to Syria in its dispute with Israel over Syrian antiaircraft missiles in Lebanon. Endorsements by other leaders, although they have not yet led to any tangible assistance, have removed Damascus from its isolation within the Arab world.

The king also criticized Syria's five-year-old role as peacekeeper in Lebanon and suggested that it be replaced by a more representative Arab froce that would try to reconcile the splintered political and religious factions there and then, after a specific time, "leave Lebanon as an independent state and a united people, as a country in peace."

The 45-year-old monarch tempered his refusal to help Syria with vague references to Jordan's support of the resolutions by last month's Arab foreign ministers' meeting in Tunisia, which pledged support to Damascus if it is attacked by Israel.

"In the face of any Israeli threat we are obviously all united," he said.

Hussein spoke in an interview with four Western reporters in his office here.It was the first major statement by the Jordania monarch since the missile crisis erupted a little more than one month ago and came four days after he returned from his first trip to the Soviet Union since 1977.

The king spoke with feeling as he sounded an essentially pessimistic note. "We are at a dangerous point," he said.

Hussein called the Arab-Israeli dispute "the most destabilizing issue" in the area and "the one that holds the key to Mideast peace." That issue, he added, also divides Jordan from "our American friends" and prevents the Arab world from being "impregnable in the face of any threats from any quarter" -- an obvious allusion to Soviet expansion.

While not attacking the Camp David accords by name, he reiterated a call for an international conference, perhaps under U.N. auspices, to engineer a comprehensive settlement for the Middle East dispute. President Leonid Brezhnev of the Soviet Union also recently renewed a longstanding Soviet call for such a conference.

Included in the conference would be Israel, the Arab states, the Palestinians, the United States and the Soviet Union. In addition, Hussein said he would bring in European states, which recently have opened an initiative, and representatives of unspecified other areas and blocs.

This would be an expansion of efforts in 1976 and early 1977 for a Geneva conference on the Middle East that would include the Soviets. This puts Hussein in parallel with Moscow and in opposition to the United States, which once regarded the Jordanian ruler as a main Arab ally.

"We have always said the Soviet Union must have a role," Hussein told the Western reporters today. "The Soviet Union and the United States and many others in this world, including Europeans, have to play a role toward any solution to this problem."

Hussein's plan, however, holds little immediate hope of success because of Israel's unswerving refusal to deal with the Palestine Liberation Organization, which is regarded by the Arab world as the only legitimate representative of the Palestinian people but by the Jewish state as a terrorist group with no standing.

The Jordanian king attacked Israel for adding what he called "a new element" to the already dangerously tense situation in the region. That, he said, is a feeling on the part off Israel that it has the absolute right to "lash out" at anyone in the area but that "no one has the right to defend itself from these attacks or to enhance their capability to do so."

"This," Hussein continued, "is a situation which is intolerable."

His comment was a clear reference to Israel's assertion of the right to fly at will over Lebanon to attack Palestinian camps in the south and to conduct aerial reconnaissance of Syrian and Palestinian movements.

Israel has threatened to attack the surface-to-air missiles Syria installed in the Bekaa Valley of Lebanon to defend its troops against Israeli air attacks.

Hussein had little to say about the peace mission of President Reagan's special envoy, Philip C. Habib, who consulted with the monarch while both men were in Saudi Arabia almost three weeks ago. But he acknowledged that Habib's mission "might have prevented at a certain point in time an eruption -- temporarily at least."

Hussein's refusal to fully support Syria underscores conflicts within the Arab world, which often seems united only in its opposition to Israel. Husseiin, for instance, backed Syria in principle against Israel: he merely said Jordan could not join it in a fight against the Jewish state.

Until late last year Syria and Jordan were considered firm friends. But Jordan was accoused of secretly aiding Moslem Brotherhood guerrillas blamed for a wave of bombings against the government of President Hafez Assad in Syria. Jordan denied the charge, but Syria in late November sent 30,000 troops to the border. At that time Hussein said, "the glass is cracked and I don't see how it can be restored." Today he called that statement "accurate" still.