The new commissioner of the Food and Drug Administration plans a multifaceted effort to restrain high prescription-drug prices, centered on speeding cheaper generic medicines onto the U.S. market.

Previous FDA commissioners have largely professed inability to act on drug costs, even as prices of drugs for cancer, hepatitis and other illnesses climbed to as much as hundreds of thousands of dollars per year or even therapeutic course. The FDA’s job, they said, is to assess safety and efficacy, and little else.

But two weeks into his tenure running the federal safety agency, Scott Gottlieb is setting an activist agenda he dubbed the Drug Competition Action Plan, on the generic-drug issue, which has until now mostly been the province of Democrats in Congress.

“Simply put, too many patients are priced out of the medicines they need,” Dr. Gottlieb told a congressional subcommittee Thursday. “While the FDA does not have a direct role in drug pricing, we can take steps to facilitate entry of lower-cost alternatives to the market, and increase competition.”

Dr. Gottlieb plans, for example, to have the agency intervene in cases in which brand-name drug companies are accused of using FDA safety rules to refuse to make drugs available to generic manufacturers. Generic companies need those products to manufacture equivalent ones.