US Secretary of State John Kerry warned Russia that it must not intervene in Ukraine under the "pretext of peacekeeping", his department said.
The statement follows Russia's version of the call, in which its Foreign Minister Sergei Lavrov was said to have called for urgent measures to avert a "humanitarian catastrophe" in the east of the country.
More top news
Team Sky's Chris Froome is set to win the 2016 Tour de France with an overall lead of four minutes 11 seconds after stage 20 to Morzine
The attempted kidnap of an RAF serviceman took place near RAF Marham, in Norfolk, on Wednesday.
Footballer Marc Crosas faces an investigation after pictures emerged of him appearing to have speared an endangered baby shark