Members of both parties on the Senate Armed Services Committee called on Defense Secretary Caspar W. Weinberger yesterday to suggest cuts in President Reagan's new $238.6 billion defense budget, and Sen. John W. Warner (R-Va.) floated as one possibility reducing the active duty military force by 5 to 7 percent.

Sen. Dan Quayle (R-Ind.) warned the resisting secretary that "these reductions are going to take place" whether he helps or not and that "we're going to get ourselves in a dangerous situation" if the Defense Department refuses to proffer cuts and leaves it to Congress to impose them.

But Weinberger said as he has repeatedly, "We simply cannot reduce defense spending any further without endangering the security of the United States."

The secretary said he was "reluctant to concede on Day One" that a carefully structured defense budget must be reduced.

The budget that Reagan sent Congress on Monday has increases for defense but not for most domestic programs, and would produce a $189 billion deficit next fiscal year. Many members of both parties have vowed to moderate the defense increase.

Warner, fourth-ranking Republican on the committee, received no encouragement from either Weinberger or Gen. John W. Vessey, chairman of the Joint Chiefs of Staff, when he suggested that the best way to bring down Pentagon spending quickly might be to reduce the active duty military force by 5 to 7 percent.

In an interview afterward, Warner said he is looking at a 5 percent reduction in the 2.1 million active duty force, which would mean taking 105,000 service men and women off the Pentagon payroll. Warner added that he has been consulting with National Guard officials to see how people discharged for economy reasons could be enticed to join reserve units near their homes where they would be on call for emergency duty.

The senator said that the 5 percent manpower cut would save between $3 billion to $4 billion, and more if related economies are counted.

Warner, like Quayle, warned Weinberger that congressional cuts in the defense budget are inevitable this year. "Nothing is certain but death and taxes and a cut by Congress in defense spending," Warner told Weinberger.

Committee Chairman John G. Tower (R-Tex.), however, stood firmly behind Weinberger in opposing cuts. Tower, declaring that there is "pork" in defense contracts, released a letter to colleagues asking them for military activities that could be eliminated in their home areas to help reduce defense spending.

In a Dear Colleague letter, Tower said he found it "intriguing" that "in one breath senators will argue for reductions in defense, and then in another breath will argue just as strongly that such reductions should not be made in programs located in their states.

"I would invite every senator," Tower wrote, "to give me a list by March 1, 1983, of any defense-related project in his or her state where a reduction of expenditures could be made because such expenditure is not essential for national defense."

Laughter broke out in the crowded hearing room at the Dirksen Office Building as Tower outlined his proposal.

Sen. Henry M. Jackson (D-Wash.), ranking Democrat on the committee, told Weinberger that he is defending his budget "at a time of changing. There cannot be a massive change based solely on the economy," Jackson said. But he added that "clearly" there could be "substantial reductions" in the president's military program which would still enable the United States "to provide a steady hand in an unsteady world."

Weinberger during several of the exchanges warned that cutting the defense budget would cost thousands of jobs and millions of dollars in tax revenues for the federal government. While stressing building up the nation's defenses was not designed to help the economy but to strengthen America and its allies, Weinberger said that "for each $1 billion cut, you lose about 35,000 jobs."

He added that "for every dollar cut in defense spending, you probably cut the deficit by 50 cents," partly because of losses of tax revenue.

Sen. Edward M. Kennedy (D-Mass.) engaged in a heated but inconclusive exchange with Weinberger on whether the United States could defend itself and allies with forces in being today. Weinberger parried several of Kennedy's thrusts by saying no one could predict how well U.S. military forces would do without knowing the type of attack.

Weinberger stressed that the United States did not possess enough strategic nuclear weapons to provide the kind of deterrence Reagan believes is needed.