Lebanese President Amin Gemayel recently raised with President Reagan the possibility of expanding the size and mission of the multinational military force now stationed in Beirut. But top American officials are not eager to get the US Marines more deeply involved in Lebanon.
Mr. Reagan was reported last week to be willing to consider a request from Mr. Gemayel to expand the 3,800-man multinational force, which includes French and Italian troops as well as some 1,200 marines. But so far no formal request has been made.
In considering such a request, Reagan would have to take into account words of caution from two of his leading advisers:
A Defense Department official says that Defense Secretary Caspar W. Weinberger, for one, wants to make sure that the marines' role in Lebanon remains a limited one. Secretary of State George P. Shultz is reported to agree with Mr. Weinberger on this.
Weinberger, says a Defense Department official, is ''very concerned about getting drawn into Lebanon a little at a time.''
''The more marines we send in, the more difficult it is to get them out,'' the official says. ''We have to do what we can to beef up Lebanon so that the Lebanese themselves can take the point position, all the way up to the Israeli border.''
''We've got a lot of rearming and training and improving to do right here at home,'' the official says. '' . . . But if you're sitting in another part of Washington, it's easy to say, 'Hey, we've got all this stuff over at the Defense Department. Let's use it in Lebanon.' ''
A Defense Department survey team headed by an Army brigadier general returned to Washington from Lebanon last week and was expected to have a report concerning Lebanon's military needs ready on Oct. 25 to present to Weinberger. This was expected to result in an expanded role for the US in the training of the Lebanese Army. The US is also expected to provide more military equipment to Lebanon. All this, however, would be a far cry from sending military advisers or more US troops.
Weinberger made his view on the possibility of expanding the present multinational force fairly clear in an interview last week with the Associated Press. The defense secretary did not categorically oppose such an idea. But when asked if he would anticipate an expansion of the force's size and mission, Weinberger said: ''I don't believe so. I would certainly hope not.''
In the interview, Weinberger suggested that countries other than the three now involved might have an interest in contributing troops to the multinational force. According to unconfirmed reports, Britain, Greece, the Netherlands, and Spain have all expressed a tentative interest in contributing.
From the beginning, the US military chiefs of staff have been extremely reluctant to get the Marines involved in the Lebanon conflict. Gen. David C. Jones, the outgoing chairman of the Joint Chiefs of Staff, made this clear in a farewell talk to reporters here several months ago.