RIYADH, Saudi Arabia — Worried about Moscow’s intentions, President Obama urged Russian President Vladimir Putin to pull his troops back from the border with Ukraine during an hourlong phone call Friday. The Russian leader, who initiated the call, asserted that Ukraine’s government is allowing extremists to intimidate civilians with impunity.

The White House and the Kremlin offered starkly different summaries of the call, which occurred while Obama was traveling in Saudi Arabia.

The contrasting interpretations underscored the chasm between how Moscow and Washington perceive the escalating international standoff sparked by Russia’s annexation of Crimea away from Ukraine.

White House officials described the call as “frank and direct” and said Obama had urged Putin to offer a written response to a diplomatic resolution to the Ukraine crisis that the U.S. has presented. Obama told the Russian leader that Ukraine’s government is pursuing de-escalation despite Russia’s incursion into Crimea, urging Putin to support that effort.

He urged Moscow to scale back its troop build-up on the border with Ukraine, which has prompted concerns in Kiev and Washington about a possible Russian invasion in eastern Ukraine.

The Kremlin, on the other hand, said Putin had drawn Obama’s attention to a “rampage of extremists” in Ukraine and suggested “possible steps by the international community to help stabilize the situation” in Ukraine.

In a statement, the Kremlin said Putin also pointed at an “effective blockade” of Moldova’s separatist region of Trans-Dniester, where Russia has troops. Russia and the local authorities have complained of Ukraine’s recent moves to limit travel across the border of the region on Ukraine’s southern border. There were fears in Ukraine that Russia could use its forces in Trans-Dniester to invade.

Both nations said Secretary of State John Kerry planned to meet with Russian Foreign Minister Sergei Lavrov to discuss further steps.

That meeting could come as soon as Tuesday or Wednesday, when Kerry is scheduled to be in Brussels for a meeting of NATO foreign ministers.

Obama, in a CBS News interview aired Friday but recorded before the call, said Russia is amassing troops along the Ukrainian border “under the guise of military exercises.”

“It may simply be an effort to intimidate Ukraine, or it may be that they’ve got additional plans,” Obama said. “And in either case, what we need right now to resolve and de- escalate the situation would be for Russia to move back those troops and to begin negotiations directly with the Ukrainian government, as well as the international community.”