Sergei Lavrov spoke hours after Ukraine claimed Pro-Russian separatists had attacked a Ukrainian navy vessel for the first time in the conflict. He told students in Moscow: Mr Lavrov said he hoped talks taking place today in the Belarussian capital Minsk today will focus on agreeing an immediate, unconditional ceasefire. Ukrainian military spokesman Andriy Lysenko said a naval cutter was attacked in the Azov Sea by artillery from the shore, and a rescue operation was under way. Separatists in the region claimed responsibility for the attack on social media. Writing on the site VKontake, former separatist military commander Igor Strelkov said: "The militia have dealt the enemy their first naval defeat." Although pro-Russian rebels have been fighting government forces since April, this is the first incident at sea. Sky correspondent Katie Stallard, in southeastern Ukraine, said regional authorities fear there were fatalities. It is not known how many people were on board the vessel. The AFP news agency said two patrol boats were attacked near the strategic port city of Mariupol.
Separatists have made significant gains in several towns close to the Azov Sea in recent days and are said to have set their sights on Mariupol.
Handout of a satellite image provided to Reuters by Supreme Headquarters Allied Powers Europe (SHAPE), showing what is reported by SHAPE a presence of Russian Self-Propelled Artillery in Ukraine
Satellite imagery reportedly shows Russian military vehicles inside Ukraine
Their advance along the Azov Sea marks the opening of a new front in their offensive, which Kiev and its Western allies say is being backed by Russian forces.
Earlier, the European Union gave Russia a week to scale back its intervention in Ukraine, warning of further sanctions.
Following an EU meeting on Saturday, Ukrainian President Petro Poroshenko warned that a "full-scale war" with Moscow was closer than ever.
"Today we are talking about the fate of Ukraine, tomorrow it could be for all Europe," he said.
Russian President Vladimir Putin has consistently denied sending in troops, but has defiantly called for immediate talks on "statehood" for southern and eastern Ukraine.
In a TV show recorded on Friday, Mr Putin said: "We need to immediately begin substantive talks... on questions of the political organisation of society and statehood in southeastern Ukraine with the goal of protecting the lawful interests of the people who live there."
His spokesman later clarified that did not mean Moscow endorsed rebel demands for independence in the areas they have seized.
Mr Putin also said the West "should have known that Russia cannot stand aside when people are being shot at point-blank range".