The United States, seeking to prevent new chaos in Lebanon after the assassination of President-elect Bashir Gemayel, yesterday appealed to Israel and Lebanon's feuding Moslem and Christian factions to avoid actions that could delay the withdrawal of foreign forces from the strife-torn country.

However, while the White House and State Department emphasized that this remains the U.S. goal in Lebanon, U.S. officials refused, in the face of repeated questioning, to criticize the movement of Israeli troops into West Beirut or to insist on their quick withdrawal.

State Department spokesman John Hughes, who was peppered with questions about Israel's action for close to an hour at his daily press briefing, said the United States was not consulted about the Israeli decision, did not acquiesce in it and favors an Israeli pullback from Beirut.

However, he added, "I'm not giving you a scenario or timetable on how that will be done."

Hughes noted that President Reagan's special envoy, Morris Draper, who is taking over the main burden of the Lebanon negotiations from Philip C. Habib, is there and is exploring with Israeli and Lebanon officials when and how a withdrawal might be made. "I think you have to give Ambassador Draper room for maneuver," Hughes said.

The spokesman also said there were "no plans whatsoever" to send back to Lebanon the U.S. marines who left Beirut last week after helping to oversee the evacuation of Palestine Liberation Organization forces from the city.

He added that his answer also applies to the possibility of putting a multinational force in Beirut.

Instead, the administration has stressed the need for restraint that will permit fast resumption of efforts to restore peace in Lebanon under a strong central government and to pursue Reagan's plan for a broader Mideast peace through new Arab-Israeli negotiations.

Administration officials said privately that there was little more the United States could do until the fast-moving events in Lebanon give a clearer picture of whether the bombing death of Gemayel on Tuesday will trigger new clashes between his Christian followers and Moslems and new tensions between the Israeli and Syrian forces there.

According to these officials, the U.S. hope is that the lid can be kept on until the Lebanese government demonstrates that it can assert authority over Beirut and then choose someone able to take Gemayel's place as president and start conciliating between Moslems and Christians.

The officials said it would be counterproductive to criticize the Israeli move into West Beirut or to make demands that might stiffen Israeli resistance before Draper has had a chance to assess the situation.

In addition, as one official privately put it, "We're not sure yet how to play it. It's hard to tell right now whether the Israeli presence is useful or not -- whether their being there for a few days will help to keep the peace or whether it will aggravate tensions."

For that reason, the officials continued, Draper, who conferred with Israeli Prime Minister Menachem Begin yesterday before going on to Lebanon, put no specific requests to the prime minister.

Instead, they said, his instructions were to remind Begin that the United States and Israel share the goal of getting all foreign forces out of Lebanon as soon as possible and to stress Washington's expectation that the Israeli forces will not stay in Beirut any longer than is necessary to ensure peace.

In line with that approach, Hughes publicly sidestepped questions about whether the Israeli military moves violated the agreement worked out by Habib for the evacuation of the PLO. He said, "It doesn't seem productive at this point to plow that ground again."

Regarding a successor to Gemayel, the officials insisted that the United States was not backing any candidate but hoped that the Lebanese would select someone sufficiently acceptable to Moslems and Christians to continue reconciliation.