Some Lebanese Christians who originally welcomed the Israeli attack on Palestinian forces here have become worried about the growing Israeli military presence in East Beirut and the behavior of troops occupying their neighborhoods.

Longtime foes of the Palestine Liberation Organization guerrillas and their Lebanese leftist allies, the Christian supporters of the rightist Phalange militia wanted to see the Israelis drive into West Beirut, crush their common enemies there and get rid of the Syrian peace-keeping troops in the country. Then, the Christians hoped, the Israeli forces would make a graceful -- and prompt -- exit.

Now the Christians are coming to grips with the realization that the Israelis are likely to do none of those things.

Some East Beirut residents find it ironic that the Israelis -- who repeatedly have accused the Palestinians of seeking to protect their guerrillas from retaliation by establishing positions in populated areas of West Beirut -- have found it necessary themselves to place more tanks and artillery in residential districts.

Among those concerned are Elias Daher and the 40 other inhabitants of East Beirut's Razmiyeh elementary school. They moved into the school from their nearby homes to take shelter from shelling directed at Israeli positions.

"What can we do?" Daher said last week as he repaired the trunk of a damaged car by the side of the school. "Even if we told you we are not happy, there's nothing we can do about it." He paused, then added: "There are small children living here, but the Israelis were firing from here and we're afraid the other side will fire back."

Directly in front of the school, which stands on high ground about 150 yards from East Beirut's Hotel Alexandre and overlooks the heavily contested museum crossing point between the eastern and western sectors of the city, sat an Israeli Merkava tank and a self-propelled howitzer. Four Israeli soldiers lounged in the school's entrance playing backgammon and listening to rock music, while two others did some maintenance work on the tank.

Asked how he felt about firing from the midst of civilians, one of the Israelis working on the tank said, "This is a city. Show me where there are no populated areas."

The blond, curly-haired Israeli expressed disbelief that the Lebanese in the school were worried and frightened by the presence of the guns. Then he said with a shrug, "This is war. I hope we don't have to shoot anymore."

Inside the school, a young mother, Antoinette Salha, said, "Everyone is frightened. It's very troublesome. The babies don't understand." Another woman with a 2-year-old child said that when the Israeli guns were firing, "We had to think of ways of shutting the babies' ears. We put on the radio and started clapping so the kids wouldn't hear the shelling."

The owner of a nearby confectionery and china shop said, "There's no question about it. When the military comes and stands next to us, we're going to be harmed. What ruined the West Side is that gunmen came and took positions among the civilian population. Now the Israelis are doing the same thing here."

Another reason for dissatisfaction among some Christians is that in pounding West Beirut and its southern suburbs with their Army, Navy and Air Force, the Israelis have destroyed or damaged a lot of property owned by Lebanese Christians. One example is a soft-drink bottling plant on the city's southern outskirts.

Some East Beirut residents also have begun to show irritation at what they see as arrogant Israeli behavior.

"They have this attitude that they can get away with anything and go anywhere they want," said one Christian woman. She said that while sitting in an East Beirut beauty parlor recently, she and other patrons were startled when an Israeli soldier carrying an assault rifle wandered in and gazed around, exclaiming, "This is just like Israel."

"He couldn"t believe it when I asked him to leave," she said. "He told me, 'but I'm not a Palestinian.' Then I asked him, 'Would I be able to go into a beauty parlor in Haifa with a gun?' "

Another Lebanese Christian, a political science student, expressed anger after an Israeli officer told her that thanks to his Army, she could now freely visit southern Lebanon for the first time in years.

"The Israelis have this attitude that they're our saviors," she said. "He told me I can go to south Lebanon as if I had been scared of the Palestinians. I wasn't afraid of the Palestinians. I was afraid of the Israelis' shelling."

Lebanese Christians also are concerned about the Israeli shekels that have been flooding the country and the terms of an unofficial trade with Israel that has gone from practically nothing to several million dollars since the June 6 invasion. Some consider it ironic that after having laid waste to urban areas in southern Lebanon, the Israelis now are doing a booming trade selling the Lebanese construction materials and seeking building contracts for Israeli companies.

Publicly, the rightist Christian Phalange Party has withheld any criticism of the Israeli occupation. But privately some Phalangist officials are resentful of the way the Israelis treat them. They are particularly suspicious of the Israeli-backed expansion of militia forces under renegade Army Maj. Saad Haddad into some areas around Sidon already held by Phalangist militiamen.

The officials complain privately that the Israeli actions on the ground contradict their stated aim of helping to establish a strong Lebanese central government, which the Phalangists hope to lead.

Usually unstated is the fear that the Christians' experience with the Syrians, who came to their aid during the 1975-76 civil war, might be repeated. The Syrians and Phalangists soon fell out, and the Syrian Army brutally pounded residential districts of East Beirut in 1978 with artillery and rockets in an effort to tame the militiamen.

"The Israelis are a foreign army," Nawal Khazen, a resident of the Christian-held port of Juniyah north of Beirut, told Washington Post special correspondent Nora Boustany recently. "And we have learned as Lebanese that the armies we throw flowers at when they come will one day turn around and shoot at us."

In fact, some expressions of respect for the Palestinian defense of West Beirut are being heard in the east these days. The comments seem to betray an Arab pride that the Israelis have not been able to advance very far into West Beirut.

"Without their Air Force," a Christian grocery store owner told a correspondent recently, "the Israelis would not have been able to take even one meter." He added, "We used to be afraid of the Israeli Army. Now we think maybe we didn't need to be so scared."