"Let me remind everybody that the Affordable Care Act is not just a website," Obama said, after the troubled online rollout of the plan.
"It's much more," he said "You may not know it, but you're already benefiting from these provisions in the law."
Obama added: "Don't let problems with the website deter you from signing up. Or signing your family up. Or showing your friends how to sign up. Because it it is worth it. It will save you money."
His ardent defense of the program came as "Obamacare" faced a barrage of criticism -- from opposition Republicans as well as usually friendlier quarters -- over technical problems with the plan.
The program, which had its official launch on October 1, aims to provide access to medical care for millions of Americans who often are priced out of other health care options.
But the healthcare.gov website has been beset by technical snafus. Phone lines were jammed and websites overloaded, making the offerings inaccessible to many who had hoped to sign up.
The launch of Obamacare went ahead despite a US government shutdown, partly triggered by Congressional opposition to the law, and the president vowed that six in 10 people could find insurance there for less than $100 per month.
On the first day of the rollout, many of the 2.8 million users the government reported having counted for the day were blocked from entering the site due to heavy traffic and technical glitches.