On Thursday, Prachanda, the rebel leader, said in a statement: "Our party once again declares a unilateral cease-fire, effective immediately, for three months."
The rebels would halt offensive operations against security services, but would remain in "active defence position," said the statement.
About 12,500 people have been killed since the Maoists began their "people's war" in 1996.
Initially seeking to create a communist republic in Nepal, the rebels now want a democratic republic and a new constitution.
The statement came days after King Gyanendra gave in after three weeks of mass protests and called for opposition parties to re-convene parliament, which was dissolved four years ago.
The royal backing down, "did not address our party, one of the key forces of the ongoing people's movement," said the rebel leader, whose name Prachanda means "the fierce one."
Once deadly foes, the rebels formed a loose alliance with opposition parties last November.
The Maoists backed an opposition-called nationwide general strike and protests that brought the country to a standstill for nearly three weeks.
The rebels declared a nationwide blockade, but have said they will wait until parliament meets for the first time on Friday before imposing the stoppage.
Opposition leaders have said that one of the first acts by the reinstated house will be to call a government cease-fire.
The rebels are calling for a constituent assembly that would draft a new constitution in order to limit the powers of the king.