The incident happened near the town of Schastia at 1115 Kyiv time on June 7, the Anti-Terrorist Operation (ATO) press center reported.
"Monitors from the SMM and the JCCC have come under fire on the positions of the Armed Forces of Ukraine from 82mm-caliber mortars not far from a bridge across the River Siversky Donets, where the monitors were taking pictures and measuring holes left by previous shelling by illegal armed groups," the report said.
The fire came from the village of Vesela Hora, which is controlled by the so-called Luhansk People's Republic.
"Shells exploded at a distance of 200 meters from the monitors. After the start of the shelling, the members of a monitoring group had to move to a safe distance. No casualties and no car damage have been reported," the press center said.
According to the source, militants shell the Ukrainian positions in that village every day, the most intensive fire was recorded on June 5 and June 6 when militants used 120mm-caliber and 82mm-caliber mortars.
"The JCCC announces that the violation of the Minsk agreements by militants was provocative and demonstrative in character, which poses a threat to the peaceful settlement of the conflict in eastern Ukraine," the ATO headquarters said.