President Obama spoke with Russian President Vladimir Putin on Thursday, emphasizing that Moscow's actions in Ukraine's Crimea peninsula violate that country's sovereignty but that a diplomatic solution is possible.
Obama and Putin spoke for an hour during the afternoon, the White House said in a statement.
The call came as ethnic Russian regional lawmakers in Crimea voted in favor of secession and moved to put the issue before voters in 10 days. Officials in Washington, Kiev and other European cities denounced the secession bid as unconstitutional.
Thousands of Kremlin troops are in control of Crimea's military, government and commercial operations. The peninsula's Moscow-backed Russian-speaking majority is refusing to be ruled by the government in Kiev, the Ukrainian capital.
During his talk with Putin, "President Obama emphasized that Russia's actions are in violation of Ukraine's sovereignty and territorial integrity, which has led us to take several steps in response, in coordination with our European partners," the White House statement said.
"President Obama indicated that there is a way to resolve the situation diplomatically, which addresses the interests of Russia, the people of Ukraine, and the international community," the statement said.
"As a part of that resolution, the governments of Ukraine and Russia would hold direct talks, facilitated by the international community; international monitors could ensure that the rights of all Ukrainians are protected, including ethnic Russians; Russian forces would return to their bases; and the international community would work together to support the Ukrainian people as they prepare for elections in May," the statement said.
The White House said Obama indicated that Secretary of State John F. Kerry would continue discussions with the Ukrainian government and "other international partners."
Crimea has become the focal point of Russia's political challenge to Ukraine's new leadership, which has filled the power vacuum created when Moscow's ally, President Viktor Yanukovich, fled Kiev last month after months of antigovernment protests.
Putin has denounced the leadership change in Kiev as an illegitimate and unconstitutional coup d'etat. He has been defiant in his defense of the military incursion, which began last week, and the prospects for a widening deployment of Russian soldiers, saying there's a need to protect ethnic Russians and strategic Kremlin interests. Russia's Black Sea fleet leases facilities in Crimea.