The subgroups are working towards finding a political solution to the armed conflict that has claimed over 6,200 lives in Ukraine's east since April 2014.
"Unfortunately, our representatives will not be able to attend the meeting of the working group on economy on June 2," Pushilin was quoted as saying by Donetsk News Agency.
He added that the schedule and dateline of the meeting "have not been agreed by consensus."
The working subgroups were set up to oversee the implementation of relevant aspects of the ceasefire deal, signed by Kiev and the self-proclaimed republics of Donetsk and Luhansk in mid-February in Minsk.
The Minsk II agreement, which was brokered by the Normandy format group of Germany, France, Russia and Ukraine, also envisions heavy artillery pullout, prisoner exchange, as well as a full restoration of social and economic connections between Kiev and the republics.
A different subgroup on humanitarian issues is scheduled to convene in the Belarusian capital next Tuesday.
