Navalny tweeted on Monday: "I will be opening a headquarters in Barnaul as if I am from the film The Mask! Cool. Even my teeth are green!" He was referring to the Hollywood film that features a superhero who wears a green mask.
The green liquid, a common Russian antiseptic that remains on the skin for days, was reportedly sprayed in Navalny's face as he went to shake a man's hand.
Navalny is currently travelling around Russia opening headquarters and campaigning to stand in the 2018 presidential elections. A criminal conviction for fraud officially bars him from running, but supporters say the charges are politically motivated.