The Israeli government, in an atmosphere of growing optimism, today expressed general approval for a U.S.-sponsored plan to get the Palestine Liberation Organization out of Beirut, and a Cabinet minister said the operation could take place within days.

But the Cabinet, meeting under Prime Minister Menachem Begin to review the U.S. proposals, expressed strong opposition to two points in the U.S. plan. They were provisions that would let the PLO retain a political office in Beirut and leave behind two 250-man military units until Syrian and Israeli forces also withdraw from Lebanese territory.

It was not immediately clear if those two points represented conditions set by the PLO or if they are American ideas on bridging the gap between what is believed to be Chairman Yasser Arafat's willingness to make a deal if he can get some face-saving formula to announce the withdrawal, and Israel's apparent intent to eradicate the PLO totally from Beirut.

In Paris today, Foreign Minister Claude Cheysson said that Arafat had communicated to the French his willingness "if the PLO political role is recognized, to step from the armed stage of resistance to the political stage." Cheysson met today with Farouk Khaddoumi, the PLO's top foreign affairs official.

Cheysson's comments raised the prospect that Arafat might be prepared to exchange some form of mutual recognition with Israel as part of a deal to extricate the guerrillas and send them to Syria, according to reports originating in Paris.

Today's action by the Israeli Cabinet followed Arafat's decision on Saturday to sign a document laying out guerrilla willingness to surrender and leave the Lebanese capital.

The result seemed to be that, while the tense Beirut negotiations are inching toward a conclusion that could avert a bloody Israeli assault on West Beirut, key Israeli objections remain and the progress of the last few days could still collapse into an onslaught against the surrounded guerrillas.

Reflecting the delicacy of Beirut negotiations among PLO leaders, Lebanese politicians and, through them, U.S. Middle East envoy Philip C. Habib, Begin dispatched Israel's top diplomat for direct talks with Habib in the Lebanese capital. The participation of David Kimche, the Foreign Ministry's director general, marked a new phase in the negotiations. High Israeli officials previously had said the talks could be compromised by such direct Israeli involvement.

Economic Planning Minister Yaacov Meridor, discussing the Cabinet deliberations, said two key developments that increased hope for an agreement now were U.S. willingness to commit Marines to police Beirut during the Palestinians' departure and Syria's willingness to accept them on its soil afterward.

President Hafez Assad of Syria, after consultations with King Fahd of Saudi Arabia, has agreed to take in the guerrillas "on condition they will slowly be removed from there," Meridor said. His comment fit in with reports here that the guerrillas likely will move by ship to the Syrian port of Latakia in a first step and then disperse in Syria, Iraq, Algeria and Egypt, according to their political orientation.

Meridor confirmed reports from Israeli officials that the Cabinet approved seven of the U.S. plan's nine main points but rejected the two points dealing with a PLO representative office in Beirut and with PLO units to be attached to the Lebanese Army pending Syrian and Israeli withdrawal.

"We cannot afford to leave this kind of thing open, because it will not be just a token. It will be a presence," Meridor said. "There should be no presence whatsoever of the PLO."

The Cabinet communique, while silent on the rest of its deliberations, also underlined Israeli insistence on removal of all PLO personnel. It said:

"Meeting in special session today, the Cabinet heard reports from the prime minister, foreign minister, minister of defense, chief of staff and director of military intelligence on the proposals for a political settlement, following which all the terrorists will leave Beirut and Lebanon, and on the events of the last 24 hours in the Beirut area."

At the same time, Meridor hinted that some PLO guerrillas could remain in the northern Lebanese port city of Tripoli, site of a large Palestinian refugee camp. This seemed to represent an Israeli concession. Previous Israeli stands--and indeed today's Cabinet communique--clearly specified that all PLO members had to leave Beirut and Lebanon entirely.

"Tripoli doesn't interest us," Meridor said. "It's Beirut we are worried about now." At another point in a series of radio interviews, he said Israel has no desire to remove Tripoli's Nahr Bared refugee camp and added: "It would be difficult to distinguish between a refugee and a terrorist."

Meridor's comments coincided with Israeli press reports that some of Arafat's PLO leadership could go to Tripoli, at least for a time, as part of the U.S. departure plan. It was unclear, however, whether this would be merely a stopover on the way to Syria or a permanent new location for some PLO leaders, conflicting with the Israeli position as described in the Cabinet communique.

Some other Israeli positions described at first as immutable have been softened in contacts with Habib during the past few weeks. There have been hints that Begin would consider a pullback of Israeli forces if it was part of an acceptable PLO departure plan, for example, and an earlier insistence that guerrillas lay down all their arms has been modified to allow them to keep personal weapons such as rifles and pistols.

In his description of the Cabinet's special session, however, Meridor underlined a deep Israeli suspicion that Arafat is simply playing for time or that he is unable to speak for some of the more hard-line factions under his PLO umbrella. Other Israeli officials also pointed to the mistrust, citing Voice of Palestine radio editorials denouncing the U.S. plan as treachery.

Meridor nevertheless depicted Begin and his government as optimistic that Habib's efforts are heading toward a conclusion. An accord is close enough that the guerrillas could begin their departure within days, he added, pointing out that U.S. 6th Fleet ships already are in the region.

High Israeli officials said Begin was incensed by yesterday's early Israeli radio report of U.S. willingness to send troops and carry out the guerrillas on American ships. The leak prompted American suspicions that Israel was trying to torpedo the plan, Begin angrily told his Cabinet, according to the officials.

The government-run radio reported the administration's decision hours before President Reagan announced it in California. Although Israeli officials refused to confirm the report at first, Israeli journalists said the leak originated in Israel.