Kerry also told Russian Foreign Minister Sergey Lavrov (SEHR'-gay LAHV'-rahf) in a call Saturday that the United States is concerned that Moscow's actions are "undermining stability, security and unity" in Ukraine.
The State Department says Kerry cited Russia's "provocative" troop movements along the border, Moscow's support for separatists and Russia's "inflammatory rhetoric."
Kerry also wants Russia to support — and not "denigrate" — Ukraine's effort to stabilize the country.
A pro-Russian insurgency accuses the German-led team of military observers of being NATO spies.
The U.S. and the world's other leading industrial powers say they're planning more economic penalties against Russia because of Moscow's actions in Ukraine.