A Monday-evening conference call between French President François Hollande, German Chancellor Angela Merkel, Russian President Vladimir Putin and Ukrainian President Petro Poroshenko resulted in the agreement for greater and more direct involvement of the Organization for Security and Co-operation in Europe (OSCE).
The OSCE would extend its monitoring at 10 flashpoint sites, including the area around the Donetsk airport, and would publish a daily report on its observations of the ceasefire agreed by the four leaders in Minsk on 12 February.
Hollande's office said "progress" was made on the ceasefire but that there was still improvement to be made.
Earlier on Monday, Hollande said the Minsk agreement could be the only basis for peace in Ukraine and warned France would "not tolerate the slightest infringement" in the ceasefire deal, which demands a demilitarisation of contested regions.
Hollande made the comments following talks in Paris with Nato secretary general Jens Stoltenberg, who cautioned Russian-backed separatists not to take advantage of the pause in fighting to launch new attacks.
Stoltenberg said France had a key and leading role in what he called the most significant change to the European security reinforcement in 25 years.
"Nato is implementing the biggest reinforcement of our collective defence since the end of the Cold War," Stoltenberg said. "France is playing a key role and a leading role."
Hollande also called on other European members of Nato to uphold their commitments to defence spending.
"We are making a considerable effort by contributing two percent of our wealth to defence," Hollande said. "We hope that many countries take into account not only what we are doing, but also what they must do to respond to different threats."
Hollande also expressed opposition to expanding the military alliance.
"France's position is to turn down would-be members. We consider that expanding Nato is not a priority at this time."