The deal only affects forces facing each other in the Luhansk region.
Separate ceasefire talks are under way in Ukraine's neighbouring Donetsk region. Heavy fighting has raged at the Donetsk airport in the past three days.
A Russian general attended the Luhansk talks, chaired by OSCE observers.
The Organization for Security and Co-operation in Europe has a monitoring mission in eastern Ukraine, where fighting has raged since the rebels seized official buildings in April.
A ceasefire deal agreed on 5 September has been violated repeatedly.
Ukraine says Russian special forces were involved in the latest Donetsk fighting, helping the separatists.
The Kremlin has repeatedly denied Ukrainian and Western accusations that it has sent tanks and troops to the war-torn region to help the rebels.
