An Israeli military patrol "nudged" a U.S. Marine with its Jeep on Monday after the Marines refused to let the Israelis pass through their checkpoint near the Beirut airport, the Pentagon disclosed yesterday.

Spokesman Henry E. Catto Jr. said the Marine was not injured. Catto said there were two confrontations on Monday as the Israelis demanded that they be allowed to pass through the Marine checkpoint to reach a village near the airport.

The Marines refused to let the Israelis pass in both instances. The U.S. government has taken the position that only Lebanese government forces and troops from the multinational force of American, French and Italian troops should be allowed to pass through Marine checkpoints in Lebanon.

The State Department through spokesman John Hughes issued this statement yesterday about Monday's confrontations:

" . . . Continued incidents of this kind can only increase tensions and violate the spirit" of the international effort to bring stability to Lebanon. "We . . . are impressing on the Israelis that such irresponsible incidents cannot recur."

Marine leaders say they believe the risk of confrontations and accidents increases the longer the American force is kept on the ground in Lebanon. Defense Secretary Caspar W. Weinberger has said he wants the Marines out as soon as possible.

However, U.S. policy makers say a continued U.S. military presence is vital to the new Lebanese government and to the negotiations to get Israeli, Syrian and Palestinian forces out of Lebanon. So the Marines' stay appears open-ended.

Against the possibility that President Reagan may decide to expand the U.S. military presence in Lebanon, specialists on the Joint Chiefs of Staff have been circulating papers with the advantages and disadvantages of various expansion plans.

Administration officials involved with Lebanese policy making have discussed the possibility of substituting Army troops for Marines, but are not inclined to do that in the near term.

They hope for a breakthrough soon in negotiations for withdrawing foreign troops, obviating the need for a U.S. Army presence in Lebanon, and they say they think a modest addition can be made to the 1,200-man Marine force in Lebanon if the president wants to join in a quick expansion of the multinational force.