Ahead of a possible ban by health authorities, the firm this month pulled its mint-flavored products after a study found it was the favorite flavor among high school students.
It now sells only three flavors in the U.S.: two tobacco-flavored varieties and menthol.
U.S. federal regulators this summer opened an investigation into potentially "deceptive marketing" by Juul.
Juul said at the time it has "never marketed to youth" but said it regretted a 2015 marketing campaign aimed at 25-34 adults that "executed in a way that was perceived as appealing to minors."
"Juul adopted the tobacco industry's infamous playbook, employing advertisements that had no regard for public health and searching out vulnerable targets," Becerra said Monday.
The lawsuit comes as the vaping industry is facing tough scrutiny amid a mysterious epidemic of lung conditions linked to e-cigarette use that has killed more than 40 people and sickened more than 2,000 in recent months.