Foreign ministers from Germany, France, Russia and Ukraine called for an end to the renewed heavy fighting in eastern Ukraine following talks in Berlin.
German Foreign Minister Frank-Walter Steinmeier said the talks had been "very controversial" at times.
He said all participants agreed there was no alternative to the ceasefire agreement signed in Minsk in February.
"We need to ensure that the ceasefire is adhered to far more strongly as fully as possible," Mr Steinmeier said.
The talks took place amid a sharp spike in hostilities in eastern Ukraine over the weekend.
Yesterday, one Ukrainian serviceman was killed and six were injured in rebel-held territories.
Mr Steinmeier said all parties had agreed to push ahead with the withdrawal of heavy weapons from the frontline.
The parties also agreed to extend this to other categories of weapons, including tanks, armoured vehicles and heavy weapons smaller than 100mm calibre.
The foreign ministers were also all willing to support the Organisation for Security and Cooperation in Europe - which is monitoring the implementation of the ceasefire deal - further with money and personnel over the next few weeks.
They also agreed to continue with an exchange of prisoners in the conflict region and to set up four working groups to deal with the humanitarian, economic and security policy questions in east Ukraine.
Mr Steinmeier stressed, however, that the Minsk accord went beyond the ceasefire agreement and must pave the way toward selections in the rebel-held territories.
"If this process stalls, then the Minsk agreement risks possibly coming off the rails ... all sides wants to prevent this," he said.
