In the first test in Congress of President Reagan's new defense budget, the House Armed Services Committee voted yesterday to hold next year's increase in military spending to 7.5 percent after inflation, 3 percentage points less than Reagan requested.

The vote was 27 to 14, and some members of the normally hawkish committee indicated that they would like to cut even further. House Democratic leaders are advocating a 5 percent growth rate after inflation.

"The present deficit situation is creating irresistible pressures for Congress to hold down defense spending," said Rep. William L. Dickinson of Alabama, ranking Republican on the committee.

The Armed Services vote came in the form of a recommendation to the House Budget Committee, which shortly will start work on a first congressional budget resolution for fiscal 1984. A 3 percent cut amounts to about $7 billion off the $245 billion in defense outlays that Reagan proposed. This year's Pentagon budget is $214 billion.

Rep. G.V. (Sonny) Montgomery (D-Miss.) said the committee vote reflected not so much a shift of opinion on defense as a "more realistic" appraisal of the mood of Congress. "If you don't slow down military spending, then we won't get to slow down other government programs," he said.

It also reflects the rivalry between the Armed Services Committee, which, for the last two years, has generally endorsed the president's budget, and the Appropriations Committee which has cut it. This year "we want to decide where the cuts are," Montgomery said.

Rep. Dennis M. Hertel (D-Mich.) said the committee was influenced by statements from such Senate Republicans as Majority Leader Howard H. Baker Jr. (Tenn.) and Budget Chairman Pete V. Domenici (N.M.), who have advocated cutting Reagan's defense budget.

"The writing is clearly on the wall," Hertel said.

Hertel said his principal concern is that the committee will choose to make cuts that affect day-to-day military readiness in such areas as fuel, ammunition and pay, "rather than weapons systems that are built in someone's district."

The two Maryland members of the committee, Marjorie S. Holt (R) and Beverly B. Byron (D), voted in favor of the 7.5 percent level, as did Rep. Dan Daniel (D-Va.).

Meanwhile, in a letter to Defense Secretary Caspar W. Weinberger, 14 Republicans, led by Reps. Marge Roukema (N.J.) and Willis D. Gradison Jr. (Ohio), called for "major savings in the defense budget . . . for the next five years. As the cornerstone of defense capability is readiness, we believe savings must come in the area of procurement."

Gradison and Roukema, writing House colleagues this week, noted that, "If no change is made in the current federal budgetary policy, we will add $1,159 billion to the federal deficit between fiscal 1984 and fiscal 1988. During this period the president is proposing a $1,593 billion defense plan."

In other action yesterday, the House Foreign Affairs Committee reported to the Budget Committee that it would stay generally within the funding levels recommended by Reagan. However, it advocated spending $1.5 billion on the Food for Peace program, an increase over Reagan's recommendation of $1.05 billion.

In the Senate, meanwhile, aides say six authorizing committees have sent recommendations to the Budget Committee and their requests exceed Reagan's budget by $8 billion, including $4.8 billion from the Environment and Public Works Committee, $1.9 billion from the Energy Committee and $1.1 billion from the Commerce Committee.

The Senate Armed Services Committee voted to support the spending levels in Reagan's budget, although Democrats on the panel indicated that they favor a cut of $9 billion in spending authority.