President Reagan said yesterday that decontrolling natural gas prices, not putting a fee on oil imports, is the answer to the economic problems of oil-producing states.

In his weekly radio address, Reagan spoke in glowing terms of his administration's oil price decontrol policies.

He said the average price of a gallon of regular gasoline has declined from $1.25 to about 82 cents since he took office in 1981. "In fact, the price of gas is now cheaper in real terms, meaning accounting for inflation, than it has been at any point since the 1950s," the president said.

Reagan went on: "I wish the entire energy picture were nothing but good news, but that unfortunately isn't so.

"While the energy-dependent states of the nation are enjoying increased economic well-being, the economies of our oil-producing states have cooled. Producers large and small have suffered a dramatic loss of income. Many small companies face bankruptcy."

But, he added, "the answer to these problems is not an import fee on imported oil. That would be a step backward. What we have to do now is go forward with actions that will further improve our energy production, freeing up all remaining energy prices. That means doing to domestic gas what we did to domestic oil -- decontrolling it."

The president said a bill sent to Congress recently by Energy Secretary John S. Herrington would be "a boon to consumers, with the average residential customer saving up to $45 . . . in the first full year of decontrol alone."

In the Democrats' weekly radio speech, Rep. Robert T. Matsui (Calif.), saying tax overhaul has been abandoned by Senate Republicans, urged the president to marshal GOP troops to rescue his key domestic priority.

Matsui said the House-passed tax-revision bill would close corporate loopholes but the pending Senate bill "bulldozes new ones."

"The Senate is giving back millions of dollars of tax breaks to corporations and special interests," he said.