Forces loyal to Ayatollah Ruhollah Khomeini staged an "Islamic Army Day" parade today as the Moslem religious leader sought to head off mounting discord and criticism.

Khomeini met in the holy city of Qom with Ayatollah Mahmoud Taleghani, the state radio said, in a apparent attempt to smooth out a dispute about the conduct of Khomeini's revolutionary militiamen that has focused discontent with Khomeini's tactics in recent days.

Taleghani went into hiding five days ago to protest the arrest of two of his sons and a daughter-in-law, giving rise to reports of a potentially serious rift between the two religious leaders. The radio said nothing of what the two ayatollahs discussed, but signed to reassure Iranians that the religious-led revolution still is united on the way to an Islamic republic.

The military parade in Tehran, organized for the same reason, seemed to many observers only to underscore the difficulties that loom ahead for Khomeini's plans, including a growing possibility of clashes between his supporters and a disenchanted coalition of Iranian Liberals and leftists.

Responding to Khomeini's call for parades to mark a hastily declared Islamic Army Day, about 10,000 soldiers marched through downtown Tehran in what experts considered a militarily sloppy exhibition. With an estimated 300,000 civilians watching or participating, the largely disorganized soldiers - some unarmed, and many with flowers in the rifle barrels or between their teeth - sang revolutionary songs, shouted slogans and danced on their tanks and trucks.

The parade displayed about a dozen British-made Chieftain tanks, 10 Russian-built armored personnel carriers and a few antiaircraft guns. Twelve F4 Phantom fighters took part in a flyover above the capital along with some transport and tanker planes and about a dozen helicopters.

"The whole thing was a little bit sad to see," said a Western military attache. "It was not very impressive."

He estimated that the number of regular soldiers who took part amounted to only a portion of the marchers. At least one-third, he said, appeared to be Islamic militiamen from Khomeini's revolutionary committees.

The procession showed what has become of the Iranian armed forces - once numbering 413,000 men - since they disintegrated during the climax of the revolution that toppled the monarchy of Shah Mohammad Reza Phalavi February.

Some military men expressed astonishment even at the small number of military aircraft the Iranians were able to put into the air under the circumstances. About 80 percent of the air force's 459 combat aircraft are grounded for lack of maintenance and inability to find spare parts.

Marches in both the army parade

In a message also broadcast by the national radio, Taleghani asked his supporters to stop demonstrating for him and called on students to go back to school. He warned against allowing "radical action" to lead the revolution to the extreme left or right.

The secret Revolutionary Council, which runs the revolutionary committees, also tried to defuse tension by issuing a statement asking Taleghani to leave his hideout and return to Tehran. The statement, broadcast before news of the Qom meeting, warned that "opportunists are using every chance for provocation and discord" in an effort to restore the shah's monarchy.

Nevertheless, small groups of Taleghani supporters continued to agitate against the committees, without actually condemning Khomeini in public.

[Revolutionary Islamic courts announced the executions of six members of the shah's personal guard early Thursday morning. The guard members, ranging in rank from colonel to private, were convicted for firing at demonstrators in Tehran's Jaleh Square on Sept. 8, wwhen more than 100 Iranians were killed and several hundred injured.]