"The reforms in the health care law ensure consumers will have access to better coverage at a lower cost in 2014," HHS Secretary Kathleen Sebelius said in a statement.
About 60 percent of men ages 18 to 34 who currently buy insurance on their own may be eligible for subsidies or expanded Medicaid programs next year, according to the report's authors, Laura Skopec, a program analyst in the HHS's Planning and Evaluation division, and Richard Kronick, the deputy assistant secretary for health policy in the division.
"Concerns expressed that millions of young men will be priced out of coverage due to the new rating reforms may be unfounded," Skopec and Kronick wrote.
Obama has been trying to combat negative public perceptions about the law that have resulted from Republican opposition as well as his administration's failures to promote and implement it.
Earlier this month, the administration decided to delay a requirement that businesses with 50 or more employees provide workers with insurance, a key part of the law's goal of expanding coverage to most of the nation's uninsured people.
Republicans seized on that decision as evidence that the law is unworkable and should be repealed. Wednesday, the Republican majority in the House voted to scale back two of the most significant provisions of the law, the individual and employer mandates.
"I recognize there are still a lot of folks, in this town at least, who are rooting for this law to fail," Obama said. "We're just going to blow through that stuff and keep on doing the right thing for the American people."
With the House bills unlikely to pass the Democratic- controlled Senate, the votes were largely symbolic measures designed to highlight opposition to the law and put Democrats on the defensive. Twenty-two Democrats voted with Republicans to delay the individual mandate, which requires most Americans to carry insurance beginning Jan. 1.
Republican-controlled state legislatures and governors also have refused to cooperate with the law's initiative to expand Medicaid coverage for the poor and declined to set up exchanges where individuals can buy insurance, leaving the job to the federal government.
The HHS report examined 2014 premiums for California, Colorado, New Mexico, New York, Ohio, Oregon, Rhode Island, Vermont, Virginia, Washington state and Washington, D.C.
All but Ohio and Virginia have been largely cooperative with the federal government in implementing the health-care law.
"It is theoretically possible that the 11 states for which we have data are not representative of the rest of the nation," Skopec and Kronick wrote. That "seems unlikely," they said, because health care costs in the 11 states are in-line with national averages, as are premiums for insurance plans sold to small businesses.
A "likely explanation" for their findings, they said, "is that greater competition and greater transparency are driving down prices" for plans to be sold in new government-run marketplaces called exchanges.