France has said conditions are "not right" for delivery of the first of two Mistral navy assault ships to Russia, reports the BBC.
President François Hollande's office blamed Moscow's recent actions in Ukraine.
France had until now resisted pressure to halt the delivery.
It had said it needed to respect an existing contract, to which EU sanctions could not apply retroactively, and that it would have been too costly to cancel.
The Vladivostok, the first of the two helicopter carriers, was expected to have been delivered to Russia by late October.
The second, the Sevastopol, was to have been sent next year, although no mention of it was made in Mr Hollande's statement.
But Mr Hollande's office said Wednesday's remarks by the Russian and Ukrainian presidents about a possible ceasefire were not enough to allow France to give it the go-ahead.
"The president of the republic has concluded that despite the prospect of ceasefire, which has yet to be confirmed and put in place, the conditions under which France could authorise the delivery of the first helicopter carrier are not in place," it said in a statement.
Read more of this report from the BBC.