Almost a week after King Hussein's surprise announcement that he would send a volunteer force to fight alongside Iraqi troops in the war with Iran, the response to the king's plan has been muted.

Inside Jordan, the government has put a tight clamp on information about the plan, its establishment and maintenance.

In the Arab world, where the press frequently assails Iran as enemy number one, the king has been praised for his stand, but North Yemen and Morocco are the only Arab states known to have answered his call to send some of their own troops.

The official Iraqi News Agency reported yesterday, however, that individual volunteers are coming from a large number of Arab states, including Egypt, Syria, and Morocco.

Syria, which is trying to whip up pan-Arab support to oppose the Israeli annexation of the Golan Heights, is not thought to view the king's campaign for similar backing for another cause with great favor.

Concern about the reaction of Syria, which has been deeply at odds with Jordan for some time, is only one of many worries on the minds of Jordanian leaders.

Indeed, the official mood here, judging from an interview with Crown Prince Hassan and private remarks by other officials, seems to be one of mounting anxiety mixed with fear and even depression about the course of Middle East events.

The kingdom, the crown prince said, sees the moderate Arab middle ground on which it depends for its survival slowly disintegrating. He cited inter-Arab and inter-Islamic feuding and the Arab world increasingly polarized by the Iranian-Iraqi war, U.S.-Soviet rivalry and Israeli aggressiveness.

As a result, Arab nationalism is dying, he said, and the possibility of ethnic breakup within several Arab nations as a consequence of the gulf war is "looming very clearly."

Hassan said he sees the Israeli annexation of the occupied West Bank, part of the kingdom before the 1967 Arab-Israeli war, as only a matter of time following the U.S. failure to prevent Israeli integration of the Golan Heights into the Jewish state.

At the same time, Jordan is bracing for a more open confrontation with Iran, possibly aided by Syria, because of the king's decision to get involved in the war. The Iranians have called his plans an "act of war."

The kingdom, the crown prince said, is caught in a squeeze between an increasingly aggressive Israel and an expansionist Iranian revolution making use of its own Shiite Islam to wage war on Sunni-dominated Arab nations it regards as enemies.

"Just to sit back and allow the Iraqis to be isolated in this, to allow the differences between Sunnis and Shiites to be exploited and the breakup of the Arab nationalist image and of the Islamic image . . . is a form of slow death," he said.

The Reagan administration's policies offer little to cheer the Jordanians either, although the deep chill that existed has been somewhat thawed by the king's trip to the United States last fall. Officials here regard the mission as a great success.

Crown Prince Hassan said a "dialogue" exists again between the two governments over the Palestinian autonomy issue. But, he quickly added, "On the question of substance, what is there to see eye to eye on?"

In fact, Jordan and the United States appear to see eye to eye on very little these days with the two on opposite sides on all key Middle East issues, except the need for peace, and there are no indications of any change in U.S. policy to give much hope of better times ahead.

The king has stood solidly against the Camp David process from the start. He also has denounced American notions to include him in the process through the so-called "Jordanian option" and has come out against the U.S. Rapid Deployment Force in the Persian Gulf, calling instead for the world's oil heartland to be made into a "neutral zone" free of superpower conflict.

Washington's displeasure with his stand has been made clear in a variety of ways, perhaps most starkly in the sharp decline in American economic and military aid. The former has dropped from $108 million in 1979 to almost nothing today, while military aid has gone from $110 million to $42 million last year.

The Jordanians have turned to France, Britain and the Soviet Union to buy arms to protect their vulnerable kingdom.

They see U.S. policy in the region as an integral part of their problems, particularly the present emphasis of the Reagan administration on the Soviet threat and East-West security issues.

The crown prince took gentle but clear issue with the present American outlook on the Middle East.

"Sometimes one has the impression the area is being compartmented into gulf security, Red Sea security and now the Iraqi-Iranian confrontation," he said. "Our feeling has always been that this is an Arab region and that gulf oil resources should be considered an economic asset to the international community with all the bases for its becoming a conflict-free zone, a neutral zone."

Neither of the superpower "proxies"--Israel with its ties to the United States and Syria with its Soviet defense alliance--should be given the chance of exploiting tensions in the region as they are today, he said.

"I think our misfortune with the United States sometimes is that we are too small and consequently too unobnoxious," he added. "We cannot manufacture crises. We can only react to them."