The US technology giant was accused of "brutal and unjustified" suspension of keyword advertisers on its platform.
"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.
"We don't contest Google's right to impose rules. But the rules must be clear and imposed equally to all advertisers."
The regulator ordered Google to clarify the "opaque and difficult to understand" rules that it imposes on advertisers.
The fine comes amid growing scrutiny of major US tech companies in Europe.
Earlier this year, Google agreed to pay €500m in France in relation to a fiscal fraud probe, as well as an additional €465m in unpaid taxes.
Google defended its policies following the latest fine, claiming they were put in place it protect users from "exploitative and abusive ads".
A spokesperson said the company would appeal the fine.
More about: Google