Some analysts said the speed limit was the initial catalyst for the gilets jaunes (yellow vests) movement.
Announcing the road deaths drop, Edouard Philippe, the Prime Minister, said the effects of the new restrictions were "without ambiguity" and that 116 lives had been saved because of them.
"We took a decision that we knew was unpopular," he said. "We are proud of the results, of the lives saved."
But 40 Millions d'Automobilistes, a French drivers' organisation, pointed out that road deaths had already started to fall at the start of 2018 before the speed limit cut was implemented. In a nod to anger over the restrictions, Philippe said it was "legitimate to discuss the issue" in the "great debate" launched by Macron in a bid to defuse the gilets jaunes revolt.