“How could we not talk about this subject?” President François Hollande of France said at a news conference afterward that was dominated by questions about the conflict in Syria.
Russia has recently deployed military forces there and begun airstrikes.
Mr. Hollande and Chancellor Angela Merkel of Germany spoke at the news conference, but the other two summit meeting participants, Presidents Vladimir V. Putin of Russia and Petro O. Poroshenko of Ukraine, did not attend.
The continuing refugee crisis, fueled in part by the war in Syria, is a source of great concern for France and Germany.
It has shifted attention away from eastern Ukraine, where a military conflict between pro-Russian separatists and Ukrainian government forces has left 8,000 people dead since April 2014 and has prompted the European Union and the United States to impose heavy economic sanctions on Russia.
In the meantime, though, there was work to do to shore up the Minsk accord, the peace agreement for Ukraine that the four powers hammered out in Belarus in February.
Mr. Hollande and Ms. Merkel offered cautious optimism about the accord at the news conference.
“Minsk is holding up,” Mr. Hollande said of the cease-fire, and Ms. Merkel agreed, even though the agreement had not been respected “100 percent.”
The accord is supposed to be put into full effect by the end of the year, and the talks in Paris were intended to iron out remaining differences.
But Mr. Hollande said on Friday that the process would probably extend beyond the end of the year.
A more recent deal was reached on the withdrawal of small-caliber weapons, and Mr. Hollande made it clear that much of Friday’s discussion focused on that.
“We wanted to insure that the withdrawal of light weapons could begin tomorrow morning at midnight,” Mr. Hollande said.
“For the heavy weapons, there would be a comparable process.”
Another major concern were contentious plans for local elections.
The Ukrainian government in Kiev scheduled balloting for Oct. 25, but could conduct it only in territory it controls.
Rebels in the breakaway regions of Donetsk and Luhansk had said they would hold their own balloting on Oct. 18 and in early November, over Kiev’s objections.
Mr. Hollande said at the news conference that “the elections on the 18th of October can’t be held.”
He said the four leaders agreed that local elections would be held under Ukrainian law, and that it would take at least three months to organize them, necessitating an extension of the Minsk accord beyond Dec. 31.
“I cannot see separatists’ winning the elections, and if they are not going to be elected, the Russians are probably not interested,” said one Western diplomat in Kiev, speaking on the condition of anonymity because of the sensitivity of the matter.
“But neither Russia nor Ukraine wants to be responsible for the failure of the elections.”
Russia and Ukraine have repeatedly pledged to carry out the Minsk accord — and have repeatedly accused each other of foot-dragging and other misdeeds.
The Ukrainian government says the Kremlin has sent thousands of troops and advanced weapons across the border into Ukraine.
Russia denies that it has any active forces there.
For its part, Russia insists that the February 2014 revolution in Ukraine was a coup plotted by the West, and it has annexed the Crimean Peninsula.
President Poroshenko of Ukraine has tried to persuade European leaders to put pressure on Moscow, imposing new sanctions if necessary, by calling the fight for Ukraine a fight for European values.
Ukrainian demands include free access throughout the conflict zone for the cease-fire monitors sent by the Organization for Security and Cooperation in Europe, or O.S.C.E.; the withdrawal of Russian military forces, military equipment and volunteer fighters from Ukraine; and the restoration of Ukrainian control over its southern border with Russia.
The first and most important provision of the Minsk accord, a cease-fire, did not materialize for months, and the fighting that erupted in the southeast in August was among the fiercest so far.
But a renewed cease-fire agreement for Sept. 1 took hold, and the area has remained largely calm since then.
The Kremlin appeared to switch its focus, talking about Syria and terrorism and Putin’s central role in defusing the global threat from the Islamic State, while Ukraine all but disappeared from Russian state-run television stations.
The longer the cease-fire continues to hold, the more willing the public on both sides will probably be to accept a compromise.
From the beginning, Russia has been talking about “federalizing” Ukraine, giving its regions much more autonomy, including the power to conduct their own foreign relations and trade policies.
The Ukrainian government in Kiev opposes the idea, seeing it as a formula for endless Russian meddling and perhaps even the disintegration of the country.
Instead, it has been pushing decentralization, a different model along the lines of France’s approach to its regions.
They would get more revenue-sharing from the national government and their councils would get somewhat more freedom, subject only to a presidential override.
A decentralization law suffered a turbulent passage through the Ukrainian Parliament, where a nationalist bloc has accused Mr. Poroshenko of caving in to Russia and taking too much presidential power.
During the vote on the bill in late August, violent demonstrations outside Parliament left three members of the National Guard dead.
Although the law was enacted, Russia says it has not been put into effect.
Russia also accuses Ukraine of violating the Minsk accord by not negotiating directly with the rebel leaders in the breakaway regions, known collectively as the Donbass.
“The people of Donbass should have their rights and interests genuinely considered, and their choice respected,” Putin said in a speech at the United Nations on Monday.
Ukraine says it is negotiating with the Donbass rebel leaders, but is doing so through the Trilateral Contact Group that was set up after the Minsk talks.
Western governments have supported continuing the talks that way.
The O.S.C.E. cease-fire monitors reported on Monday what appeared to be clear evidence that Russia had transferred heavy weapons to the rebels.
The monitors said that at a military training area in Luhansk, they saw a Russian-made launching system called a TOS-1, nicknamed Buratino, which can fire rockets with highly destructive thermobaric or fuel-air warheads.
The Kiev government has been asserting for more than a year that Russia has supplied that type of weapons system and others to the separatist rebels, while Russia has denied any involvement in the conflict in eastern Ukraine other than supplying humanitarian aid.
Source: The New York Times