Syria announced the conclusion of its spring military maneuvers near Israeli positions today, a decision that took some of the edge off fears of imminent conflict along the Syrian-Israeli confrontation lines in eastern Lebanon.

Syria's military maneuvers near the Golan Heights, which Israel has annexed, had heightened anxiety here as Israeli officials publicly recalled how such war games had served as cover for Egyptians in the 1973 Arab-Israeli war.

Israel put some of its troops on alert yesterday and sent in tanks and reinforcements as Deputy Prime Minister Moshe Levy pointedly warned Syria that it was "playing with fire."

In announcing an end to the war games and a return to a "normal situation," the official Syrian news agency SANA said the soldiers had "proven during the maneuvers their high capacity to repel all aggression to which the Army is exposed."

In Williamsburg, U.S. officials spoke of "aggressive behavior" by the Syrians and called the situation "dangerous." Story, A32.

Syria and Israel in recent days have accused one another of preparing acts of aggression in a war of words as both sides are reinforcing their positions along their front lines.

Syrian Prime Minister Abdul Rauf Kasm, in a speech today in Damascus that reflected the tone of the verbal conflict, said Syria was not preparing to attack but "we shall fight if we have to."

Saying Israeli aggression was "mounting daily," he indicated that the Soviet Union would come to the aid of Syria if that became necessary.

Syrian President Hafez Assad was reported by the Beirut daily Al Safir to have secretly visited Moscow last weekend, according to Deutsche Presse-Agentur. A senior delegation from Fatah, the largest Palestinian guerrilla group, will visit Moscow next week at the invitation of the Soviet leadership, the Palestinian news agency WAFA reported. The agency said the delegation would be led by Salah Khalaf, known within the PLO as Abu Iyad, who is a senior official of the group.

Reporters in Syrian-held territory of eastern Lebanon's Bekaa Valley today observed convoys of trucks and buses heading east toward the Syrian borders.

Journalists in northern Israel near the Lebanon frontier observed new armored personnel carriers, tanks, troop buses and ammunition trucks traveling into Lebanon.

The Israeli military command, in a delayed report, said one Israeli soldier was killed and two were wounded Friday in an ambush by Palestinian guerrillas along the cease-fire line in the Bekaa Valley. It said one guerrilla also was killed.

All of this military movement has frightened the residents of the Bekaa Valley and elsewhere. Radio announcers in Beirut who deliver the news often do so these days in nervous voices.

Tensions remained high in Beirut after East Beirut and predominantly Christian suburbs were shelled by heavy artillery for about five hours early this morning as part of the revenge duels of warring Lebanese Moslem Druze and Christian militiamen who had renewed their fighting late yesterday in the mountains overlooking the capital.

Nine persons were injured before Israeli Army officers occupying the mountains were able to arrange a shaky truce between the two factions. Four previous cease-fires had produced only lulls in the shelling, some of them only 10 minutes long.

"Every time we reached a cease-fire in one area, the fighting started again in another area," said Lebanese Forces Christian militia spokesman Fady Hayek. He blamed the Druze for starting the battles; they blamed the Christians.

These various actions and movement of troops have been confusing for Western military analysts.

The analysts say they know Syria has reinforced its forces in Lebanon but they do not have a precise idea of how much. They also say they know Syria has redeployed its forces in the past two months. But they add that these may be routine movements from "winter positions" to strategically advantageous locations now that the weather has cleared and the ground hardened.

There is similar bewilderment about what Israel is up to. The character of its reinforcement of troops in recent days does not appear to indicate that it is preparing for a preemptive strike against Syria. One analyst said they "appear to be normal precautions to forestall being caught napping."

In the midst are numerous rumors, many of them floated on local radio, that are not confirmed but increase fears.

One such rumor today reported Syrian firing on Israeli reconnaissance planes over their positions. Another, taken more seriously by analysts, suggested that Syrians had brought into Lebanon medium-range SA6 ground-to-air missiles.

Israeli reports that Syrians had fired on their planes and helicopters on Wednesday had been the trigger for the current crisis. Syrians, slow to acknowledge that there had been any incident, later said their MiG fighters had intercepted Israeli planes because of what they described as violation of "air space of Syrian forces."

Israel has repeatedly conducted air reconnaissance operations over Syrian positions. At the same time, Israel considers the air space over its own positions in Lebanon to be restricted and has frequently canceled routine helicopter flights by United Nations peace-keeping forces without explanation.

The internal Lebanese battles in the mountains are not viewed here as being directly related to the Syrian-Israeli confrontation although the heavy shells being fired in that conflict come from guns behind both Israeli and Syrian lines.

The belief is that those battles which have raged off and on since the fall have been stepped up recently because of signals by Israel that it soon intends to withdraw from the mountains. The theory is that both Druze and Christians are maneuvering for advantage in preparation for the day when Israel leaves.