The American Medical Association passed a resolution today calling for a halt to federal subsidies to the tobacco industry, reversing an AMA policy going back about 15 years.

Delegates representing about 40 percent of the nation's doctors at the AMA's annual convention voted to "support the elimination of the federal price support program for tobacco." The action will pit the strong doctors' lobby in Washington against tobacco subsidies.

Though the AMA has declared smoking a health hazard and refused to accept tobacco advertising in its publications, in the past the association always refused to support an end to tobacco subsidies.

But today the 283 delegates went with a resolution pushed by medical students and young residents. They said smoking is the number one preventable cause of death in the country, costing the lives of 320,000 annually from smoking-related illnesses.

The students found today's vote somewhat contradictory to yesterday's action in which the AMA refused to divest itself of its stock in tobacco companies. AMA has $1.4 million in tobacco stocks out of $113 million in the retirement fund.

Objections to the vote on federal subsidies came from the Kentucky delegation. "The price support has no applicability to smoking," said Dr. Harold Haller of Kentucky. "It's a farm issue. . . . We hate smoking, too. But the AMA has no right to challenge the small farmer." He said the price support program limits the poundage of tobacco a farmer can produce and thus prevents large growers from crowding smaller farmers out of the market.

Ronald Davis, a third-year medical student from Chicago who introduced the resolution in the House of Delegates, said, "This is a significant action, let me tell you. We've tried to pass five resolutions like this in the pass 14 years, but each time they've been watered down."

Davis said the price support programs costs $60 million to $80 million a year. According to an aide to Sen. Walter D. Huddleston (D-Ky.), the cost is closer to $12 million annually.

In other action, the delegates rejected a committee recommendation supporting stronger federal gun control laws. With little debate, the doctors voted to table the issue indefinitely.