The Senate Armed Services Committee is calling for a major redirection of President Reagan's Strategic Defense Initiative (SDI), and for a possible slowdown if that will help persuade the Soviet Union to agree to real reductions in nuclear weapons.

In its report on next year's Defense Department authorization bill, the committee said "the major emphasis" of SDI research should be on a "survivable and cost-effective" defense of U.S. strategic forces and not on "comprehensive, nationwide population protection," which has been Reagan's stated goal.

In addition, the committee said the United States "should be prepared to consider adjustments to the pace and scope of SDI if the Soviet Union agrees to significant, stabilizing and verifiable reductions in strategic offensive forces."

In the latest round of Geneva arms talks, which concluded Thursday, the Soviets said that if the United States agreed to continue adherence to the 1972 Antiballistic Missile (ABM) Treaty for 15 years they were ready to negotiate reductions in strategic arms. Defense Secretary Caspar W. Weinberger and others have said this would kill SDI, popularly called "Star Wars," altogether.

The committee recommended what it called a "robust" SDI program of $3.9 billion for next year, $1.5 billion below the president's request. Such a program, the committee said, was "realistic" to meet the threat from Soviet defense research and at the same time provide leverage for U.S. negotiators in Geneva.

In a broader look at Pentagon research, the committee said SDI spending was leading to a sharp reduction in basic technology research directed at other areas of weapons development. It called for reallocating $453 million from the SDI request to other research.

Principal authors of the language refocusing SDI and calling for a balanced technology program were Sens. William S. Cohen (R-Maine) and Sam Nunn (D-Ga.).

The committee report called the funding profile for SDI in the next five years "excessive," in light of the basic design and what it termed disagreement over the goals.

Lt. Gen. James A. Abrahamson, in a luncheon with reporters and editors of The Washington Post yesterday, defended his program and said there was no disagreement within the administration over its goals. The aim is to protect both populations and missiles, he said.

In another action, the Armed Services panel eliminated funds for production of two controversial Navy nuclear weapons, the antisubmarine warfare (ASW) missile and the SM2 standard antiair missile. Sen. Edward M. Kennedy (D-Mass.) initiated this cut. The two weapons also have been eliminated by Congress in past years.

The House Armed Services Committee also cut out the ASW nuclear weapon in its version of next year's authorization bill.