Access to e-cigarettes by kids is a "big concern" for the Food and Drug Administration, and the agency plans to take steps soon to better address the vaping problem.

Make no mistake, e-cigarettes contain nicotine, FDA Commissioner Dr. Scott Gottlieb told CNBC on Friday, adding they're becoming increasingly popular among young people.

"If all we end up doing is addicting a whole new generation on nicotine through e-cigarettes, then we will have done a bad service to this country," he said on "Squawk Box."

The FDA on Thursday made good on a promise last summer and issued a formal notice of proposed rulemaking for maximum nicotine levels for traditional and e-cigarettes. The agency is seeking input on what that level should be and guidance on whether to implement that new standard all at once or gradually.

Gottlieb said the FDA wants to transition smokers to "modified risk tobacco products" — which are said to pose lower health risks — or have them quit altogether.

"It's really the first step in the rule-making process to try to pursue regulations that will ultimately lead to a reduction in nicotine levels in cigarettes," Gottlieb said Friday.

In 2016, more than 2 million U.S. middle and high school students used e-cigarettes over a 30 day period, according to the Centers for Disease Control and Prevention. The CDC cautions that nicotine exposure can harm adolescents' brain development, which can continue into their 20s.

Gottlieb, who previously served as a senior policy advisor for the Centers for Medicare and Medicaid Services under President George W. Bush, said if adults want access to nicotine, the preferred route from the agency is through medicinal products.

"We're taking a lot of steps try to increase the pathway towards medicinal nicotine products, like a patch or a gum," Gottlieb said.

Last year, the FDA announced a plan for tobacco and nicotine regulation, to the surprise of some tobacco companies, with the goal of encouraging the development of new products that are less dangerous than cigarettes.