European Commission President Jose Manuel Barroso has said it is "critically important" to find a diplomatic solution to the Ukraine crisis.
Barroso called on Russia to engage constructively, saying a real deescalation is "in the interests of everyone in Europe, including Russia."
He also urged Moscow not to use energy as a political weapon.
He was speaking after talks with Ukraine's Prime Minister Arseniy Yatsenyuk in Brussels on May 13, one day after the European Union expanded financial sanctions
against prominent Russians and Crimeans.
During Yatsenyuk's visit to the EU headquarters, Ukrainian and European officials signed agreements to allow the disbursement of 1 billion euros ($1.37 billion) in EU aid for Ukraine.
Earlier on May 13, German Foreign Minister Frank-Walter Steinmeier said on a visit to Kyiv that Germany will assist efforts to start "roundtable talks" between Ukraine's government and its opponents in the east of the country.
Steinmeier also stressed the importance of holding Ukraine's presidential vote as planned on May 25.
Yatsenyuk said the key to resolving the destabilizing situation in Ukraine "is not in Kyiv but in Moscow."
Steinmeier's trip to Kyiv is part of the road map for settling Ukraine's crisis laid out by the Organization for Security and Cooperation in Europe (OSCE) this week.
The OSCE plan calls on all sides to refrain from violence and urges amnesty for those involved in the unrest as well as talks on decentralization and the status of the Russian language.
In Moscow, the Russian Foreign Ministry called for a swift implementation of the OSCE plan.
It said its demand to end violence means Kyiv authorities should stop their military operation against pro-Russian separatists in eastern Ukraine and pull back its troops.
It said it expects the separatists to respond "adequately" if Kyiv does all that.
Deputy Foreign Minister Grigory Karasin was quoted as saying the Ukrainian government's "unwillingness to lead a real dialogue with representatives of the regions" is a "serious obstacle for deescalation."
The Ukrainian government has said it was ready to hold roundtable talks but said leaders of the armed rebels in the east would not be allowed to participate.
Pro-Russian separatists in Ukraine's eastern Donetsk and Luhansk regions declared the regions' independence on May 12, one day after so-called self-rule referendums.
Ukrainian authorities denounced the votes as a "farce" and Western states rejected them as illegal.
Separatists in Donetsk also asked Moscow to consider "absorbing" the region.
Ukrainian Troop Deaths
In an apparent escalation on May 13, seven Ukrainian soldiers were reported killed in an ambush by pro-Russia separatists in the restive east.
The Ukraine Defense Ministry said a convoy of armored vehicles was attacked outside the city of Kramatorsk by more than 30 separatists who were using grenade launchers and automatic weapons.
The ministry said at least seven other soldiers had been wounded.
It was the single biggest loss of life since the Ukrainian army was deployed against armed separatist groups who have seized control of towns and public buildings in the east of the country.
Before the Kramatorsk incident, authorities had said a total of nine servicemen had been killed in the army's "antiterrorist" operation.
The European Union on May 12 imposed sanctions on a further 13 Russian and Crimean individuals and 2 Crimean companies over the crisis.
With reporting by AP and AFP