During their telephone call, the US and French leaders also discussed the hunt for more than 200 kidnapped schoolgirls in Nigeria and a conference Hollande is hosting in Paris this weekend on combating the Islamic militant group Boko Haram that is holding them.
"The presidents underscored that Russia will face significant additional costs if it continues its provocative and destabilizing behaviour," the White House said in a statement.
"President Obama praised the Ukrainian government's efforts to unify the country by holding free and fair presidential elections on that will lead to an inclusive constitutional reform process."
Washington has warned Russia that it could face "sectoral" sanctions directly targeting its economy if it is judged to have disrupted the Ukrainian election.
The statement did not say whether Obama had urged Hollande to cancel the $1.6 billion sale of two French-built helicopter carrier ships to Moscow, which the US government has described as inappropriate following Russia's actions in annexing Crimea.