President Trump said the U.S. plans to pull most vaping products from the market, citing growing concerns about health hazards and rising use by teenagers of the trendy alternative to traditional cigarettes.

The Food and Drug Administration intends to ban popular fruity flavors, as well as menthol and mint e-cigarettes from stores and online sellers, leaving just tobacco-flavored products. The move poses a major threat to a fast-growing market estimated to reach $9 billion in sales this year and dominated by startup Juul Labs Inc., which counts on mango, mint and other fruity flavors for most of its sales.

Public-health officials have encouraged adult smokers to switch to less risky products such as e-cigarettes, which deliver nicotine in a cloud of vapor. Tobacco companies have invested in the technology to offset declining sales as smokers switched to new entrants like Juul. But the sleek devices also proved popular with teens and young people who had never smoked. About eight million adults use e-cigarettes, and about five million children are also vaping, including more than a quarter of high-school students, according to the latest government estimates.

“We have a problem in our country. It’s a new problem,” Mr. Trump, a Republican, said in the Oval Office on Wednesday as he met with top health officials. “It’s called vaping, especially vaping as it pertains to innocent children.”

The move comes as officials are investigating more than 450 potential cases of pulmonary illness related to vaping products, many of them containing marijuana. Six deaths in the U.S. have been associated with the illness. The latest death, reported Tuesday, was a Kansas resident over the age of 50, the state’s health department said.