White House press secretary Jay Carney told reporters that Russia has an “easy way out” of the international crisis.
Carney said teams from the United Nations or the Organization for Security and Co-operation in Europe could monitor the situation in Crimea and protect civilians.
Russian military forces took control of the Ukrainian region of Crimea over the weekend, with Moscow claiming that they were protecting the safety of the majority-ethnic Russian population in the area.
But President Obama has dismissed that defense, accusing Russia of violating international law by moving forces into the neighboring state.
Russia's critics say Putin is seeking to reassert his influence over Ukraine after Moscow-backed former Ukrainian President Viktor Yanukovych was removed from power by an interim government in Kiev.
Carney told reporters aboard Air Force One en route to an event in Connecticut that the administration wants Kiev to ensure that the rights of ethnic Russians in Ukraine are protected, but added that there was no sign they were in danger.
Obama has said the administration will weigh a full range of measures to respond to Russia, warning that there will be “costs” to Moscow’s actions.
On Tuesday, the president said that there was still time to “de-escalate” the situation, but said Russia should allow observers on the ground.
Putin has said that Russia does not seek a conflict with Ukraine, but has ignored calls to remove troops from Crimea, saying that Moscow has a right to protect ethnic Russians.
Reports on Wednesday said Russian lawmakers were threatening to seize assets of Western firms in retaliation for any sanctions. An unconfirmed report also said that armed gunmen had threatened a U.N. envoy in Crimea.
Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov are meeting in Paris on Wednesday to discuss ways to end the standoff.
Obama is facing pressure from Congress to take tougher steps to rein in Moscow, but European allies are unlikely to back calls for sanctions on Russia, with whom they share close economic ties.
Carney said the U.S. was taking steps alone and in concert with allies to help Ukraine and respond to Russia’s military venture.
The administration announced Tuesday that it will offer $1 billion in loan guarantees and financial assistance to Ukraine to help stabilize its economy.
House Speaker John Boehner, R-Ohio, also called for the U.S. to take steps to send more natural gas to Ukraine to help it escape its dependence on Russian energy. House lawmakers vowed Wednesday to quickly pass legislation offering aid to Ukraine.
The European Union also announced that it would offer $15 billion in aid over the next two years.