PARIS—France’s competition authority fined Alphabet Inc.’s Google €150 million ($167 million) for unfairly suspending advertisers that placed allegedly deceptive ads, the latest in a series of antitrust probes and decisions against big tech firms in both Europe and the U.S.

The French authority on Friday said Google abused its dominance of the market for ads displayed in search results by suspending those advertisers in France in a random and unpredictable fashion, imposing significant losses on those sites.

The authority ordered Google to pay a fine and to stop the “brutal and unjustified” suspensions of search advertisers and to clarify its rules for advertisers. The authority also said that Google should have a system to alert advertisers when they risk suspension from its ads system.

“Google has the power of life or death for certain companies that live by these advertisements,” said Isabelle de Silva, chairman of France’s competition authority, at a press conference to announce the decision. “We don’t contest Google’s right to impose rules. But the rules must be clear and imposed equally to all advertisers.”

Google said it would appeal the ruling in court, adding that it the company stands by its decisions to remove what it called “exploitative and abusive ads” from its platform.