President Reagan's decision to send U.S. troops into Lebanon a second time met with a mixture of nervous approval and doubt on Capitol Hill yesterday, as members of Congress called for the withrawal of Israeli troops from Lebanon and questioned Israel's role in the massacre of Palestinian civilians this weekend.

"I'm sure the president will get the support of the Senate," said assistant Senate majority leader Ted Stevens (R-Alaska). "But a lot of us are going to hold our breath."

Sen. Henry M. Jackson (D-Wash.), however, warned the move "could lead to real trouble. As a superpower, it is not wise for us to move into an extremely unstable situation. We're going right into the fire on this one, where revenge, revenge, revenge is the order of the day."

Reagan needs no approval from Congress to send in the Marines, but is required under the War Powers Act to notify Congress and can only keep troops on foreign soil for limited periods without congressional concurrence. Congress also has leverage over the issue through its power of the purse, which covers both military outlays and U.S. aid to Israel.

The divisions in Congress were not along partisan lines. Republican Sens. Larry Pressler (S.D.) and John W. Warner (Va.) opposed the president's new plan, while Democrats Alan Cranston (Calif.), Gary Hart (Colo.) and Paul E. Tsongas (Mass.) reluctantly approved it.

Initially, members were cautious about criticizing Israel, but as more was reported about the massacre throughout the day and members were briefed by Central Intelligence Agency and State Department officials, senators and congressmen became increasingly critical of the involvement of Israeli troops in the incidents.

"Words are not adequate to express the revulsion we all feel at the killing of men, women and children in West Beirut," said Sen. Edward M. Kennedy (D-Mass.). "I believe that Israel, as a functioning multi-party democracy, should urgently carry out an open and public investigation as to how this tragedy occurred and how it might have been prevented, to establish accountability and to take any appropriate action."

Claiborne Pell (R.I), ranking Democrat on the Senate Foreign Relations Committee, said Israeli Prime Minister Menachem Begin "is a dangerous man. He's gone too far. They Israelis are shooting for a Pax Judaica, peace on their own terms. . . . Israel has to accept residual responsibility [for the massacre]. They should have stayed out of West Beirut."

Foreign Relations Chairman Sen. Charles H. Percy (R-Ill.) said, "Eyewitnesses saw the Israeli forces allow the militant Christian forces to go into those camps and apparently placed no restraints or restrictions on them. We want the Israeli forces out of West Beirut. We want all foreign forces out of Lebanon."

Sen. Patrick J. Leahy (D-Vt.) said, "Israel cannot evade its measure of responsibility for the violence that is shaking Lebanon to its foundations. The savagery of the Christian militias who were permitted to enter the Palestinian refugee camps by Israeli forces, makes a terrible mockery of Israel's claim of preserving order for its military move into West Beirut."

Talk circulated in the Senate that Israel's multibillion-dollar foreign aid and military aid package could be cut, perhaps by the amount used to invade Lebanon. "The massive U.S. economic and military assistance program gives the U.S. leverage to obtain the removal of Israeli occupation forces in Lebanon," said Pressler, a member of the Senate Foreign Relations panel.

Rep. Dante B. Fascell (D-Fla), a senior member of House Foreign Affairs Committee, said he backed sending peace-keeping troops "providing we have an agreement with the Israelis, the Syrians and the Lebanese as to the withdrawal of all foreign forces. . . . I'm not interested in being in the middle of a civil war."