Lekhnath Newpane, head of the All Nepal National Independent Student Union Revolutionary, told reporters on Sunday at a village about 80km southeast of the capital, Katmandu: "We will not allow the municipal elections to take place at any cost."
He said the rebels would not allow the government to use schools and colleges as polling stations.
The group also said: "We will track down those who file for candidacy in the election and make sure they withdraw their names."
Newpane refused to say what means the group would use to disrupt the elections planned for 8 February in 58 cities and towns across the Himalayan kingdom.
Nepal has not held municipal elections since 1998 because the previous poll, scheduled for 2003, could not be held because of rebel violence.
Newpane has been in hiding since the Maoist rebels, who claim to be inspired by Chinese revolutionary Mao Zedong, began fighting in 1996 to replace the constitutional monarchy with a socialist state. Violence in the monarchy has claimed about 12,000 lives.