MOSCOW—Russia’s antimonopoly watchdog fined Alphabet Inc.’s Google 438 million rubles ($6.75 million) on Thursday for competition violations, the latest step in a long-running and high-profile legal battle.

The fine comes ahead of a court appeal later this month by Google against the watchdog’s ruling that it violated laws by bundling, or pre-loading, a suite of apps on mobile phones for sale on the Russian market. The legal battle goes to the heart of a struggle for Russian market share between Google and Russian technology...