Russia's ambassador to the United Nations Vitaly Churkin has told an emergency meeting of the Security Council that Moscow "does not want war" with Ukraine.
Responding to a direct question from Ukraine's interim Prime Minister Arseniy Yatsenyuk, Mr Churkin gave an impassioned defence of Crimea's right to hold a referendum on whether to join Russia.
Mr Yatsenyuk had told the council on Thursday that his country was a victim of Russian aggression, and held up a copy of the UN Charter to make his point that Moscow is violating it and several other international treaties.
However, he said he still believed "we have a chance to resolve this conflict in a peaceful manner" and urged Moscow to meet for direct talks.
Mr Yatsenyuk spoke in English, then dramatically switched to Russian to address Mr Churkin directly, saying that Kiev was "looking for an answer to the question whether Russians want war" with a country with whom it has "for decades had warm and friendly relations".
"I'm convinced that Russians do not want war," Mr Yatsenyuk said. "I hope that the Russian government and the Russian president will heed the wishes of their people and that we return to dialogue and solve this conflict."
In reply, Mr Churkin said: "Russia does not want war and nor do the Russians, and I'm convinced that Ukrainians don't want this either. Furthermore, we do not ... interpret the situation in such terms. We don't want any further exacerbation of the situation."
Mr Churkin did not respond to Mr Yatsenyuk's request for talks, but said the referendum in Crimea had come about because of a "legal vacuum" in the country and Crimeans should be "afforded the opportunity" to decide on their future.
Warnings if referendum goes ahead
US Secretary of State John Kerry has warned of a "serious series of steps" against Russia if the Crimean referendum goes ahead on Sunday, and British foreign secretary William Hague has called for the referendum to be abandoned, saying European Union sanctions will be stepped up if there is no progress in the "next few days", the BBC reports.
German Chancellor Angela Merkel has also warned that Russia risks massive political and economic damage if it continues to destabilise the situation in Ukraine.
Mr Kerry is due to meet his Russian counterpart Sergei Lavrov to discuss the crisis in London on Friday, amid fears that Moscow is attempting to annex the mainly ethnic Russian autonomous region of Crimea.
He will try to persuade Russia it risks paying a heavy price in political and economic damage from American and European measures which could be triggered by the referendum.
Meanwhile, Russian president Vladimir Putin has told a meeting of his security council that this is an inter-Ukrainian crisis that "arose not through our fault, but we are involved in it, one way or another".
He said he wanted to discuss how to "build relations with our partners and friends in Ukraine and our other partners in Europe and the United States".
In a sign the tension may be spreading, Belarus - a Russian ally - has asked Moscow to deploy extra fighter jets and military transport aircraft after Nato boosted its forces in the neighbouring Baltic countries.
Military exercises on border resume
Earlier, the Defence Ministry in Moscow announced that military exercises by thousands of Russian troops would be resumed in the regions of Rostov, Belgorod and Kursk, which border Ukraine, and continue until the end of March.
It said the exercises involve rocket launchers and anti-tank weapons and the main aim is a "multi-faceted check of the units' cohesiveness followed by the performance of battle training assignments in unfamiliar terrain and untested firing ranges".
Similar exercises were carried out near Ukraine's eastern and southern frontiers in February.
Ukraine's national security chief Andriy Parubiy warned on Thursday of what he called a critical situation on the borders, saying there is a "threat of a full-scale invasion from various directions" and warning that some Russian troops are just two to three hours from Ukraine's capital, Kiev.
Fighting in Donetsk
Violent clashes have broken out between rival groups of protesters in the eastern Ukrainian city of Donetsk, the BBC reports.
One person was killed and a number were wounded when hundreds of demonstrators chanting pro-Russian slogans are said to have confronted a rival rally by people opposed to the Russian military intervention in Crimea. It is thought the protesters broke through a police cordon.
Ukrainian television reported that some people were carrying knives and metal rods.