Moody's held its French credit rating at Aa1 but maintained a negative outlook, days after President Francois Hollande announced a batch of business-friendly measures to fire up growth.
The US agency affirmed the bond rating one notch below the top AAA rating.
Moody's voiced scepticism about the reforms Hollande announced earlier this month, a "responsibility pact" which includes lowering labour taxes in exchanges for fresh hiring by companies.
"The implementation and efficacy of these policy initiatives are complicated by the persistence of long-standing rigidities in labour, goods and services markets as well as the social and political tensions the government is facing," the agency said in a statement.
"I can only welcome" this announcement, French Finance Minister Pierre Moscovici told reporters at the World Economic Forum in in Davos, Switzerland.
The latest rating of French credit by Standard and Poor's, the leading rating agency, is two notches below the top level.
The French government had feared that Moody's might decide a further downgrade but the agency said any reassessment of the rating and outlook would hinge on the results of the latest moves to bring back jobs and growth.
"Moody's would consider moving the outlook to stable and eventually upgrading France's government debt rating should the rating agency conclude that the planned economic reforms and fiscal measures are both implemented and effective," it said.
The agency said that so far "competitiveness issues have led to a gradual erosion of France's export-oriented industrial base and constrain the economy's shock-absorption capacity and, ultimately, its long-term growth potential".