"As Ukrainian positions are still being fired upon there can be no talk yet of a withdrawal of weapons," military spokesman Vladyslav Selevnyov wrote in a statement on Facebook.
Ukraine's military said Monday that it is waiting for a full ceasefire with pro-Russian rebels before withdrawing heavy weapons from the frontline, a key next step in a tattered peace plan.
Seleznyov said that Kiev was only willing to start pulling back its heavy weapons once there has been a total stop in firing for a whole day.
Ukraine's military said that clashes overnight dropped off considerably but that insurgent fighters had briefly tried to storm a flashpoint village east of the key government-held port city of Mariupol.
Elsewhere around the conflict zone Kiev said its forces had only come under fire twice during the night.
Separatist rebels said Sunday that they had reached an agreement with Kiev to start withdrawing weapons and would complete the pull-back by March 7.
A ceasefire was meant to start February 15 under the terms of a European-brokered peace plan but the truce never got off the ground as rebels made an all-out assault to capture the transport hub of Debaltseve.
A withdrawal of heavy weapons to create a buffer zone along the frontline was meant to start within 48 hours of the ceasefire coming into effect.