"The Syrian government said it would cease fire at 6:00 a.m. local time (0300 GMT) on April 12. Now the ball is on the armed opposition's court," Gatilov wrote in his Twitter microblog.
He stressed the opposition's stop of fighting was also a condition stipulated by UN-Arab League joint envoy Kofi Annan.
Also on Wednesday, Syria's official SANA news agency and Annan' s spokesman both confirmed the Syrian government's will of a truce.
Damascus' announcement came in compliance with the deadline given by the United Nations for the implementation of a ceasefire brokered by Annan to solve the Syrian crisis politically and save the country from plunging into an all-out civil war.
The six-point proposal put forward by Annan has set April 10 as the deadline for troop withdrawal and April 12 as the deadline for a complete ceasefire between the Syrian army and rebels.