Lebanese Christian militiamen have foiled, at least for now, an Israeli Army effort to evict them from their barracks. The Israeli move was blocked by a sit-in demonstration swelled by hundreds of men, women and children from the Christian villages nearby.

Israeli spokesmen in Beirut and Jerusalem said yesterday that Israeli troops had attempted to oust the Lebanese Forces militiamen from their barracks and had successfully removed several who had resisted the order to move out. But visitors to the barracks in the hilly village of Kfar Falus east of this southern Lebanon port city learned today that while Israeli armor and troops were there in force, no one could be said to be truly in control.

Later this evening, spokesmen for the Lebanese Forces, the Phalangist militia, in Beirut announced that they had reached an agreement with the Israeli Army for a withdrawal of Israeli troops from the barracks in exchange for the militia's promise to end the sit-in. Israeli spokesmen did not confirm the report.

This afternoon, in the courtyard in front of the old yellow Romanesque stone villa that has been the Kfar Falus barracks for the Lebanese Forces, Israeli soldiers perched passively atop armored personnel carriers while throngs of villagers, including men and women carrying babies, streamed in and out.

A Lebanese teen-ager sat on the sidelines tapping idly at a bongo drum. From elsewhere came the strains of rock music. Some of the elderly who had participated in the sit-in overnight were taking an afternoon nap on makeshift foam rubber mattresses under military tents.

Last night, a Lebanese Forces spokesman here said, villagers brought in folk instruments and danced until 5 a.m., with some of them grabbing Israeli soldiers for partners.

"We are still friends," the spokesman said, referring to the erstwhile alliance of the Israelis and Christian Phalangists that had become strained over the past week as the Israeli Army attempted to extend its control over unruly southern Lebanon.

Israeli spokesmen said yesterday that they had moved to shut down the barracks because of the failure of militiamen to coordinate their activities with the Israeli Army, which is occupying southern Lebanon. In Jerusalem, spokesmen were reported to have mentioned the militia's unauthorized roadblocks and of Palestinian and Lebanese Moslems.

Lebanese Forces spokesmen here said the rift emerged because of theirdemands to merge with the Israeli-backed forces of former Lebanese Army major Saad Haddad, whom the Christian militiamen indicated they regard as something of a quisling.

Last week, Israeli officers here gave commanders of the Kfar Falus barracks an order to leave, which they refused. Before dawn yesterday, Israeli armor and troops encircled the compound in an effort to evict them forcibly.

The Christian militiamen acknowledged that they are outgunned in the confrontation, but that has not deterred them.

"We do not pretend that we can fight Israel," said Phalangist Party leader Pierre Gemayel. "The Israeli Army is one of the strongest in the world and our forces among the weakest in the world and we realize that very well.

"But, just as we are very careful not to touch the dignity and the honor of the Israelis, we hope that they will exercise the same care that they will not touch our dignity."

With no possibility of a military response, the Phalangists relied on the demonstrations by villagers. Yesterday, residents burned tires, blocked traffic and rang church bells to protest the planned eviction. They sponsored a general strike in nearby Christian villages that shut down restaurants, shops and offices. And then they sat in at the barracks.