Secretary of State George P. Shultz said yesterday that the administration does not plan to expand the size or mission of the U.S. Marine force in Beirut because the Lebanese government appears able to control the violence there.

In a news conference, Shultz also acknowledged that the Marines are in an area where "there has been a renewed outbreak of violence." But he turned aside questions about whether the situation requires a congressional review, under the War Powers Act, of whether the Marines should be kept in Lebanon.

Shultz asserted repeatedly that President Reagan has been complying with provisions of the War Powers Act that require him to keep Congress informed. However, when reporters asked about another provision barring the president from keeping forces abroad in hostile situations for more than 60 days unless Congress gives permission, Shultz took refuge in legal ambiguities about the meaning of the act.

His responses appeared to be an attempt to shunt aside calls for a congressional review from some members of Congress, who were joined yesterday by Senate Minority Leader Robert C. Byrd (D-W.Va.) and Senate Foreign Relations Committee Chairman Charles H. Percy (R-Ill.).

Since Sunday, when the animosities among Lebanese factions erupted into violent new fighting in which the Marines came under attack, Shultz had stayed in the background while the White House handled administration statements on the situation from its vacation headquarters in Santa Barbara.

In what appeared to be a move to deal with congressional concerns, Shultz, who is widely respected on Capitol Hill, yesterday took over as principal administration spokesman. He reiterated U.S. support for Lebanese President Amin Gemayel's government, while seeking simultaneously to assure the public and Congress that this support is not expected to require the dispatch of more American Marines into life-threatening hostilities.

Shultz said he does not believe that the Marines, who suffered two dead and 14 wounded in fighting on Monday, had been singled out as targets, but he added that messages intercepted by the United States in Beirut had left the situation unclear.

"There are conflicting statements," he said. "You get an intercept here or there about somebody saying to shoot at the Marines, and you also get many intercepts that say, 'Oh, the Marines are there. Don't shoot at the Marines.' "

"I believe there is no concerted effort to single out the Marines and target them," he concluded.

In calling for Congress to consider the Lebanon situation under the War Powers Act, Byrd and Percy joined a chorus that already included Sen. John Glenn (D-Ohio), Sen. Charles McC. Mathias Jr. (R-Md.), Rep. Clement J. Zablocki (D-Wis.), chairman of the House Foreign Affairs Committee, Rep. Michael D. Barnes (D-Md.) and Rep. Ike Skelton (D-Mo.).

Sen. Barry Goldwater (R-Ariz.) and Rep. Samuel S. Stratton (D-N.Y.), both influential members of the Armed Services committees in their respective houses of Congress, have gone further and called for withdrawal of the Marines.

On Tuesday, Reagan formally notified Congress that the Marines had been involved in "sporadic fighting," but he declined to describe the fighting as "hostilities," which is the operative term in the War Powers Act.

Percy, in an interview published by the Kewanee, Ill., Star Courier, said: "We have people up in helicopters. We're shooting rockets and artillery. If that isn't imminent hostilities, I don't know what it is."

Zablocki charged yesterday that the president's action was "misleading." He said that "any combat veteran knows that when shooting goes on as intensively as it has in Beirut, there are 'hostilities'--particularly when those rounds are aimed at you."

"In persisting in trying to exclude the Congress from fulfilling its constitutional responsibilities in this situation, the president is unnecessarily risking a confrontation with Congress," Zablocki asserted.

However, with Congress in recess until Sept. 12, the Reagan administration is understood to believe it can stave off for several more days any concerted attempt to force a showdown over whether the continuing Marine presence in Lebanon should be subjected to formal congressional review under the War Powers Act.

In the meantime, as Shultz made clear yesterday, the administration is counting on the hope that the Lebanese army will be able to quell the fighting in Beirut and make moot the question of whether the Marines are involved in hostilities.

When Shultz was asked if the Marines are in a combat situation, he replied: "The question now is whether the efforts being made to control and end the violence will succeed. . . . The authorities of the central government of Lebanon are working at that . . . .Our advice is, and our own independent observation is, that they are moving in the right direction. So assuming that it subsides, then I think we're back in the situation we were in before."

The secretary opened his conference with a lengthy statement in which he said, "At present we are advised by the Lebanese central authorities that effective measures are being taken to restore order. We all pray that they will be successful."

Shultz then called attention to the call issued by Gemayel yesterday for "a dialogue" between the country's feuding factions and said, "We intend to help President Gemayel in his new initiative in every way possible."

Shultz, who was a Marine officer during World War II, said the U.S. Marine contingent serving with French, Italian and British units in the multinational force will remain in Lebanon. "Let no one doubt that if attacked, the Marines will take care of themselves with vigor," he added.

Asked whether effective help for Gemayel will require increasing the number of Marines and broadening their mandate to take them out of their present, essentially defensive positions around the Beirut airport, Shultz replied: "We have no plan under consideration at the moment to change the size or the role or the mission of the multinational force or the Marine component of it."

The secretary also sought to soften harsh criticism directed by the White House against Syria, which scuttled a U.S.-mediated agreement for withdrawal of Israeli forces from Lebanon by refusing to pull its troops out of the country. On Monday, a senior White House official, who declined to be identified, charged that Syria was playing "a spoiler role . . . with Soviet encouragement."

Shultz said he had no evidence that Syria had incited this week's attacks on the multinational force. He stressed, though, that peace in Lebanon requires the withdrawal of all foreign forces, and said, "I think it would be a very large contribution if that very large Syrian army would agree to get out of there."

In his letter to Reagan, Byrd argued that the Marines "are clearly involved in hostilities within the meaning of Section 4(A)(1) of the War Powers Resolution" passed by Congress in 1973 as a response to allegedly unauthorized commitment of troops to Vietnam. It sets up procedures under which the president must consult Congress before sending troops abroad and report back to Congress thereafter.

The section cited by the Senate minority leader bars the president from keeping military forces in hostile situations abroad for more than 60 days unless Congress has declared war, authorized the specific troop deployment or extended the time period for another 30 days.

The administration complied with the act's reporting provisions when it committed the Marines to Lebanon last year. But it did so in a way that did not trigger the 60-day authorization period, and Congress until now has stopped short of trying to force the issue.