U.S. President Barack Obama spoke with German Chancellor Angela Merkel Friday about the crisis in Ukraine.
The White House said in a statement the president agreed with European leaders on the need for Russia to pull back its forces, allow for the deployment of international observers and human rights monitors to Crimea, and support free and fair presidential elections in May.
The White House statement said Mr. Obama and Chancellor Merkel discussed the need for Russia to "agree quickly" on the formation of a contact group, leading to direct dialogue between Ukraine and Russia "to de-escalate the situation and restore Ukraine's territorial integrity."
Meanwhile, in a telephone conversation Friday with U.S. Secretary of State John Kerry, Russian Foreign Minister Sergei Lavrov warned the U.S. against taking any "hasty and reckless steps" that could harm Russian-American relations. Lavrov said the sanctions would hit the U.S. "like a boomerang.:"
Earlier Friday, armed men smashed a Russian military truck through the gates of a Ukrainian missile defense post in the Crimean peninsula.
The men negotiated with the base's commanders as soldiers sheltered in their barracks Friday. No shots have been reported.
Also Friday, Ukraine's Interim President Oleksandr Turchynov signed a decree canceling a planned referendum on Crimea joining Russia.
A day earlier,Crimea's Moscow-backed legislature voted for the peninsula to become part of Russia and scheduled a referendum on the issue for March 16.
Ukraine's interim prime minister says that "no one in the civilized world" will recognize the referendum's results.
Arseniy Yatsenyuk says he wants to "warn separatists" and others he describes as "traitors of the Ukrainian state" that their decisions are "unlawful" and "unconstitutional." U.S. and European leaders also called the referendum illegal.
Crimean officials fired back Friday, saying the vote will go forward.
The speaker of Russia's upper house of parliament said Friday Russian lawmakers will support Crimea's decision if the Ukrainian region decides to join Russia. Tens of thousands of people turned out for a rally in the Russian capital to show solidarity with Crimea's pro-Russian authorities.
Ukraine and Russia have been locked in a tense standoff since Russian forces entered the Crimean peninsula a week ago.
Also Friday, Russian President Vladimir Putin's spokesman said he hoped that Russia and the West do not return to a period of tensions like the Cold War.
Russian news agencies quoted Dmitry Peskov as saying that despite "profound disagreements" between the two sides, "the hope remains that as a result of dialogue it will be possible to find some common ground."
Still, Peskov dismissed the idea that Western countries could mediate talks between Russia and Ukraine.
Ukrainian Prime Minister Yatsenyuk said Friday his government is "prepared to rebuild relations with Russia." But he said Russia must withdraw its troops, fulfill its agreements with Ukraine and stop supporting separatists in Crimea.
President Obama spoke by phone Thursday with Russian President Vladimir Putin about the Ukraine crisis, but the two leaders found little common ground.
The White House says Mr. Obama told Mr. Putin the presence of Russian forces in Crimea is a violation of Ukraine's sovereignty. The Kremlin says Mr. Putin denounced Ukraine's new government as "illegitimate" and said Russia cannot ignore calls for help from Ukraine's Russia-leaning east and south.
Also Thursday, Mr. Obama authorized sanctions, including visa restrictions, against those found to have violated Ukraine's territorial integrity. The EU also took measures against Russia, suspending talks on visas and a new economic agreement.