California's cannabis czar issued a cease-and-desist order to Weedmaps.
The regulator claims the Irvine-based company is promoting businesses that don't have a license to sell pot.
Weedmaps and its competitor Leafly.com are digital guide books on where to buy marijuana and related products.
Weedmaps makes its money from selling ad space to dispensaries.
Now that recreational pot is legal, California wants Weedmaps to stop selling ad space to businesses not licensed by the state. As of March 1, Leafly.com removed such ads.
Weedmaps officials say they are a search engine, and the same information can be found on Google and other sites.
California regulators say there is no immediate plan to fine Weedmaps.