"The president underscored the need for the United States, European Union and other global partners to be prepared to meet further Russian escalation with additional sanctions," the White House said in a statement about the phone call.
Pro-Russian separatists in eastern Ukraine, "apparently with support from Moscow, continue an orchestrated campaign of incitement and sabotage to undermine and destabilize the Ukrainian state," it added.
"The leaders again called for Russia to move its troops back from the border region."
Earlier in the day at World Bank/IMF meetings in Washington, US Treasury Secretary Jacob Lew delivered the same warning to his Russian counterpart Finance Minister Anton Siluanov, ramping up the pressure on Moscow.
Ukraine is facing a new secession crisis following its loss of Crimea to Russia, and relations between Moscow and the West have hit new post-Cold War lows.