The White House said President Barack Obama urged Russian President Vladimir Putin in a phone call to agree to a peace deal.
"If Russia continues its aggressive actions in Ukraine, including by sending troops, weapons, and financing to support the separatists, the costs for Russia will rise," the White House statement added.
The Kremlin, in its statement about the call, said Putin and Obama highlighted the need for the need for a political solution to the "internal" conflict in Ukraine.
The Kremlin also said the two leaders also noted the necessity to safeguard the rights of inhabitants of all Ukrainian regions, including Russian-speakers in the east.
Video footage recorded from Kramatorsk, deep inside Ukrainian-government controlled territory, shows rockets landing on civilian areas.
Video footage appears to show the moment a shell strikes a community soup kitchen in eastern Ukraine.
A mother in eastern Ukraine buries her son - yet another casualty in a civil war that is killing civilians with appalling randomness.