According to Kiev officials, the army virtually sealed off the town of Mykolayivka after attacking six posts of separatists.
Four soldiers were reportedly injured as a result.
No official comments have been made by the leadership of the self-proclaimed “Donetsk People’s Republic”, which claims control over the region where Mykolayivka lies.
Clashes between pro-Russian activists in Ukraine’s Donetsk and Luhansk regions were renewed after a temporary ceasefire between rebels and so-called “anti-terrorist” units expired this week.
Wednesday saw a fresh diplomatic initiative to deescalate the situation, with Foreign Ministers of Ukraine, Russia, Germany and France agreeing to start talks on a new truce in the Donbass by Saturday.