Russia said on Sunday it was calling its ambassador to Ukraine back to Moscow for "consultations", AFP reported.
"Due to the escalation of the situation in Ukraine and the necessity of analyzing the existing situation from all sides, a decision has been made to recall the Russian Ambassador to Ukraine (Mikhail) Zurabov to Moscow for consultations," the foreign ministry said in a statement quoted by AFP.
Earlier Sunday, Oleksander Tuchynov, the new speaker of the Ukrainian parliament and a supporter of Yulia Tymshenko, was elected interim president. He will hold the position until elections on May 25.
Tymoshenko, who was released from prison on Friday following a vote by parliament, was received on Saturday night by thousands of opposition supporters in central Kiev.
"You are heroes," she told the crowd on Independence Square, the focus of protests against Yanukovych.
"Until you finish this job and until we travel all the way, nobody has the right to leave," she added. "Because nobody could do it - not other countries, nobody - could do what you have done. We've eliminated this cancer, this tumor."
Tymoshenko had been sentenced to seven years in jail after a controversial verdict on her actions as prime minister.
Meanwhile on Sunday, the United States’ National Security Adviser, Susan Rice, issued a warning to Russian President Vladimir Putin against attacking Ukraine.
Speaking on NBC’s “Meet the Press”, Rice said that it “would be a grave mistake” for Putin to intervene militarily in the Ukraine crisis.
She also told the program that “the United States is on the side of the Ukrainian people” and wants to see democratic elections and “the opportunity for the people of Ukraine to come together in a coalition unity government” after Yanukovych was toppled.