"Ceasefire violations and fighting, in particular near Mariupol, Shchastya, Donetsk airport and the area of Shyrokyne, must end," the French president's office said in a statement after the leaders held a four-way telephone call.
The statement came as the Ukrainian military and pro- Russian rebels reported four more people killed in clashes in the past 24 hours, over two months after they agreed a ceasefire aimed at ending a conflict that has killed over 6,000 people.
The rebels said one of their fighters had been killed in fighting that also killed two civilians, one in rebel- controlled Donetsk and the other in the flashpoint town of Shyrokyne.
Shyrokyne is located near the southeastern port of Mariupol, the largest city still under government control in the conflict zone.
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The conflict began in April 2014, when the separatists took up arms against Kiev following Russia's annexation of Ukraine's Crimea peninsula.
A wobbly truce has been in place since mid-February, but the two sides continue to trade fire in a handful of areas.
"The release of prisoners and humanitarian aid must be facilitated," they added, according to the French presidency statement.