"We think that we must be extremely firm and that, if an agreement is to be reached, that agreement must be robust," Fabius told journalists at a joint news conference with Israeli Prime Minister Benjamin Netanyahu, who strongly opposes the deal currently on the table.
"That means that it must be able to be verified."
European foreign ministers will meet their Iranian counterpart Mohamed Javad Zarif tomorrow, ahead of a June 30 deadline for an international accord on Tehran's nuclear programme.
The world powers and Iran set themselves the deadline of June 30 to finalise what would be a highly complex accord, and negotiators have been meeting regularly in Vienna and elsewhere in recent weeks.