Russia has been accused by the West of arming and bankrolling a rebellion in eastern Ukraine, a charge Moscow denies.
But sanctions imposed by the European Union and the United States on Russia have complicated France's commitment to the 1.2 billion euro deal to deliver the two Mistral-class warships -- even though the order was made long before the crisis erupted.
"There needs to be ... a process of ceasefire that is respected and a political roadmap that would lead to the return of peace and calm," Jean Yves Le Drian told Europe 1 radio station.
"I see that efforts are being made, but as long as they are neither tangible nor verifiable, we cannot make a decision," he added.
A September truce, followed by another ceasefire deal, has helped calm the heaviest fighting but clashes continue in eastern Ukraine. Kiev has reported the deaths of nearly 20 soldiers in the past three weeks.
Paris said late November that it was delaying delivery of the first warship, which was set for autumn 2014, "until further notice."