As Ukrainians rallied on Sunday, leaders of several nations continued to pursue diplomacy. Prime Minister David Cameron of Britain and Chancellor Angela Merkel of Germany both spoke with President Vladimir V. Putin of Russia. Mr. Cameron’s office relayed that Mr. Putin “said that Russia did want to find a diplomatic solution to the crisis” and “agreed that it is in all our interests to have a stable Ukraine.”

By the British account, Mr. Putin said he would discuss proposals for a contact group, which the West envisages involving direct talks between Moscow and Kiev.

The German government said Ms. Merkel made it clear that any Crimean referendum was illegal and that it would not be recognized internationally. On Thursday, the chancellor said that if a contact group was not formed soon and no progress was made in negotiations with Russia, the European Union could impose sanctions on Russia, including travel restrictions and the freezing of assets.

According to the Kremlin’s account of the call, however, Mr. Putin “underlined in particular that the steps taken by Crimea’s legitimate authorities are based on international law and aimed at guaranteeing the legitimate interests of the peninsula’s population” and that Kiev was not acting “to limit the rampant behavior of ultranationalists and radical forces in the capital and in many regions.”

Image People attended a pro-Russian rally in Feodosia in Crimea on Sunday. Credit... Sergey Ponomarev for The New York Times

The Kremlin statement continued: “Despite the differences in the assessments of what is happening,” the three leaders “expressed a common interest in de-escalation of the tensions and normalization of the situation as soon as possible.”