"He will have to deal with local terrorist groups and anything that threatens public safety in Mindanao," presidential spokesman Ernesto Abella said at a news briefing on Tuesday.
Mindanao, an island of 22 million people, was placed under martial law on May 23 after rebels from the ISIL-affiliated Maute and Abu Sayyaf groups took over parts of Marawi City.
Government forces are clearing the city while a fraction of ISIL militants are still fighting there, scattered all over the downtown area and in tall structures.
Over 530 people including Islamic militants, civilians and government forces soldiers have been killed during airstrikes and street battles in the past two months.