BEIRUT, JULY 21 -- Turbaned Shiite clergymen brandishing assault rifles today led thousands of demonstrators -- bearded men, and women clad in black chadors -- through the central Lebanese town of Baalbek, urging Moslems to intensify their terrorism and shouting chants against America and France.

The massive, two-hour rally was held to show solidarity with Iran in its diplomatic dispute with France and to underline Iranian rejection of a resolution passed yesterday by the U.N. Security Council calling for an end to the Persian Gulf war.

Walking slowly to the cadence of refrains shouted through truck-mounted loudspeakers by members of Hezbollah, a militant, pro-Iranian organization, the marchers, according to journalists on the scene, called on Moslems to "escalate terrorist acts, and the jihad {holy war}, and fight darkness with more terrorism."

About 4,000 well-organized demonstrators swept through Baalbek's narrow streets, chanting: "No one can humiliate Iran. A self-willed people will never be crushed. Remain terrorist you Moslems. Only terrorism will keep your heads high."

Hezbollah clergyman Sobhi Tufeili, one of 12 Iran-backed mullahs making up the consultative council of the radical Shiite grouping, said the rally was "the first day of battle against evil.

"A few of the downtrodden in Lebanon were able to defeat America and its allies and we shall transform gulf waters into a mass grave for the bodies of Americans and non-Americans," Tufeili added.

Addressing France and America, the crowds shouted, in apparently rehearsed unison: "You are threatening us with a severance of ties; remember the gravesite of the {French} paratroopers in Lebanon. You are threatening us with your fleets in the gulf; remember the burial ground of the Marines in Lebanon."

France broke relations with Iran this week in a dispute over French demands to question an Iranian Embassy aide over bombings in Paris.

"Stamp with the sole of your shoe on the head of the spy Chirac," the marchers said, describing French Prime Minister Jacques Chirac as President Reagan's "spoiled brat."