President Reagan insisted yesterday that his missile defense program, the Strategic Defense Initiative (SDI), will not become a "bargaining chip" in arms control negotiations with the Soviet Union.

The president also urged Congress not to slash spending for the program.

Reagan's comments, in his weekly radio address from the presidential retreat at Camp David, come on the heels of reports that the latest Soviet arms proposal has sparked renewed discussions of a possible delay in deployment of the missile defense system in exchange for deep cuts in the superpowers' offensive arsenals.

Such a tradeoff has been privately discussed intermittently over the last year by senior policy-makers in the administration. In his public statements, including a news conference last September, Reagan has repeatedly ruled out such a tradeoff.

The Soviets have frequently attempted to block Reagan's missile defense plan. Last week, French President Francois Mitterrand said after meeting Soviet leader Mikhail Gorbachev that it remains one of the key stumbling blocks to a superpower arms agreement.

Reagan said yesterday that his missile defense program, popularly known as "Star Wars," would make nuclear missiles less effective and thereby more negotiable.

"And when we talk about negotiations, let's be clear. Our SDI research is not a bargaining chip. It's the number of offensive nuclear missiles that need to be reduced, not the effort to find a way to defend mankind against these deadly missiles," he said.

Reagan did not specifically address the Soviets' latest arms control proposal. That proposal, which the president earlier described as the beginning of a serious negotiating effort, links continued adherence to the 1972 Anti-Ballistic Missile treaty with reductions in offensive missiles.

The administration, which is preparing a response to the Soviet offer, remains sharply divided over whether to accept restraints on the missile defense program as part of a compromise arms control agreement. Defense Secretary Caspar W. Weinberger and his chief adviser on arms control, assistant secretary Richard N. Perle, have argued against any such compromise.

Yesterday, Reagan reiterated warnings that the Soviets are making an "intense effort" to develop their own strategic defenses and have built "the world's only anti-ballistic missile system."

"These Soviet strategic defense programs have been termed 'Red Shield' in an article in this month's Reader's Digest," Reagan said. " . . . In stark contrast, we are defenseless against the most dangerous weapons in the history of mankind. Isn't it time to put our survival back under our own control?"

Reagan also criticized efforts in Congress to reduce sharply his request for $5.4 billion in Star Wars spending in the year that begins Oct. 1. He said it would be a "tragedy to let the budget pressures of today destroy this vital research program and undercut our chances for a safer and more secure tomorrow."

Reagan said this research has made progress in such areas as sensing, targeting and intercepting enemy missiles. He also said Britian, West Germany and Israel have signed agreements with the United States to cooperate in the research effort.