The Maute group is one of less than a dozen new armed Muslim groups that have pledged allegiance to the Islamic State and formed a loose alliance with Hapilon reportedly designated as the alliance's leader.
He added: "To my countrymen, do not be too scared".
"Unfortunately I must go there now", he said.
- Who are the militants?
The goal yesterday's raid was to capture Isnilon Hapilon, a leader of the Abu Sayyaf group which is notorious for piracy and for kidnapping and beheading Westerners. The US government is offering a $5-million bounty for his capture.
Hapilon, the man whom Philippine soldiers had sought at the start of the operation, "allegedly served as deputy or second in command for the foreign terrorist organization, Abu Sayyaf Group", according to the Federal Bureau of Investigation. Duterte arrived yesterday in official visit to Russian Federation, for strengthening the cooperation in terms of defense and security, as well as economy, commerce and especially in agriculture.
"Lahat ng gagawin na dapat gawin sa [Everything that needs to be done during] martial law, we will implement".
But the Abu Sayyaf, Maute and other hardline groups are claiming they want to set up an Islamic caliphate in the south for IS, according to security analysts.
Mr Duterte earlier declared martial law for 60 days on Mindanao, where Muslim rebel groups are seeking autonomy.
Clash between government forces and the Maute group erupted yesterday, May 23, in Marawi City after the military raided an apartment where 15 members of the IS-linked group were seeking refuge.
Duterte warned that martial rule in Mindanao would be "harsh" similar to the one declared by the late strongman Ferdinand Marcos Sr. almost half a century ago.
But Aquino said he decided against it partly because military rule could spark resentment among local people.
Kabataan Representative Sarah Elago said Martial Law is a "blanket endorsement for so many abuses including warrantless arrests, searches and seizures".
Brigadier General Rolando Bautista, commander of the Philippines' First Infantry Division, said security forces were trying to locate militants who had scattered everywhere and were blocking reinforcements from arriving.
During the nine years of martial law under Marcos, police and troops tortured, abducted and killed thousands of people who were critical of the dictatorship, according to rights groups and historians.
Duterte-Carpio said police and army authorities did not discount the possibility of terrorists and bandits to enter the city given previous incidents.
Martial law allows the use of the military to enforce order and the detention of people without charge for long periods.
The post-Marcos constitution imposed safeguards on martial law, including the requirement for congress to approve its imposition and extension. The Supreme Court may also review the basis of its declaration.
As of writing, Malacañang has not yet issued the document bearing Duterte's martial law declaration.