Violence escalated after a deal between the two sides was blocked
Nearly 130,000 people have fled their homes following renewed fighting in the southern Philippines between the army and Muslim rebels, officials have said.
There has been controversy in the region over a deal to expand a Muslim autonomous zone there.
The tensions in North Cotabato province came a week after a formal deal on the expansion was blocked by the courts.
The military said the violence would not halt voting in elections in the nearby autonomous region of Mindanao.
Voters there are choosing a new governor, vice governor and members of a regional legislative assembly.
North Cotabato is not part of the vote, because it is not included in the five-province Autonomous Region of Muslim Mindanao, which was created in a 1996 peace accord between the government and Muslim rebels.
Troops began their attack on Sunday, after Moro Islamic Liberation Front (MILF) rebels in North Cotabato ignored a 24-hour deadline to leave the area.
Soldiers continued to bomb Muslim rebel positions for a second day on Monday.
They regained control of two villages, and are still aiming to regain 13 others, military vice chief of staff Lt Gen Cardozo Luna told the Associated Press.
At least one soldier and seven rebel fighters have been killed since the attack began.
Reports say many of the villages still occupied by the MILF are on the provincial border of mainly Christian North Cotabato and mainly Muslim Maguindanao.
The rebels are said to be frustrated at the fresh obstacles towards agreeing to expand the Autonomous Region of Muslim Mindanao (ARMM).
Regional tensions have grown since the plan was agreed, with Christians fearful of the greater powers that would be granted to rebels.
The expanded zone, which would be subject to approval in a local plebiscite, would include another 712 villages.
Local leaders would also be entitled to a large share of the region's rich resources.