"California won't be doing business with Walgreens - or any company that cowers to the extremists and puts women's lives at risk. We're done," Newsom tweeted.
Walgreens announced the decision last week to halt the distribution of mifepristone in 20 other states after anti-abortion lawmakers in those states urged them to do so.
In a statement on Monday, Walgreens said it plans to dispense mifepristone in any jurisdiction where it is legally permissible to do so.