NATO Secretary General Lord Carrington today warned the West against being tempted by Soviet efforts in Geneva to link reductions in offensive nuclear weapons to U.S. abandonment of research on its Strategic Defense Initiative.

In a meeting with American correspondents here, Carrington cautioned against giving "things away before the hard bargaining actually starts." He did not specify the target of his warning. But his remarks seemed to be addressed to government and opposition factions in NATO countries contending that the Reagan administration has taken an intransigent position on the SDI, or "Star Wars" program, at the U.S.-Soviet arms talks set to resume May 30 in Geneva.

"What the United States does with SDI is for the United States to decide," Carrington said. He suggested that the Soviet Union, perhaps spurred on by anxious U.S. allies, should not be the one to set the terms under which arms control negotiations should proceed.

Carrington said that despite the appeal that such an offer -- promising reductions in offensive missiles for curtailment of SDI -- might have to public opinion in the West, it would be "meaningless" since it "isn't verifiable" at the research stage and there would be no way of knowing if Soviet research on a similar space-based defense system would be ongoing.

"If the Soviet Union is worried in the future about deployment of SDI," Carrington said, "it could look for some kind of treaty, and there is a precedent with the ABM treaty."

The Soviets have placed a priority on curtailing space-based defensive systems as a condition for offensive missile cuts. The administration has said that it will discuss the SDI program but its research phase is not negotiable. It has supported that argument with assertions that Moscow is far along in its own such research program.

A number of the NATO allies have expressed concern over the ultimate deployment of such space defense weapons. But despite the fact that Norway, Denmark and France have said they will not accept a U.S. invitation to participate in SDI research, NATO defense ministers meeting in Luxembourg in March pledged their support for the research phase of the program.

Pressure has continued, however, within some members of the North Atlantic Treaty Organization, particularly West Germany, the Netherlands and Belgium, for a firmer U.S. indication that SDI would be negotiable under certain conditions -- including the offer of a major Soviet reduction in offensive nuclear weapons.

U.S. officials are known to be especially concerned about the West German government of Chancellor Helmut Kohl, who has been attacked within his own party and by his political opposition for being too supportive of Reagan.

Carrington argued today, and in a speech yesterday in London, that Reagan already has made a pledge, in his speech to the European Parliament in Strasbourg last week, to discuss space weaponry before any unilateral deployment.

Reagan said that "when the time for decisions on the possible production and deployment of such systems comes, we must and will discuss and negotiate these issues with the Soviet Union."

In the meantime, Carrington said, the prospect of drawn-out negotiations in Geneva makes a united NATO front vital: "The opportunities for the Soviets making trouble between the Americans and Europeans are there. Not only on SDI.

"The problem is going to be to keep a consistent, united front in the face of what are likely to be two or three elections every year in Europe. A consistent East-West strategy within an alliance of 16 is very difficult to maintain."

Criticizing his fellow Europeans, Carrington, an ex-foreign minister of Britain, said that Western Europe "has the tendency to adopt a policy of referee or umpire. It's our position, not just the American position, but the alliance position. It is very important not to let this sort of thing develop."

From the Soviet point of view, he said, it is worth stalling and waiting for fissures to develop in the natural course of democratic politics.