The anti-riot police and thousands of protesters have engaged in intense pushing and shoving along Faura Street and Taft Avenue in Ermita, Manila.
Wooden planks and slippers were seen being hurled by demonstrators at the cops.
Some persons were wounded, including four policemen.
The commotion prompted the Philippine National Police (PNP) to use water cannons against the protesters.
They have also deployed trucks to block the demonstrators who are trying to head to Roxas Boulevard and at the Philippine International Convention Center (PICC) where the Association of Southeast Asian (ASEAN) Summit is being held.
Police initially thought the protesters would march towards the United Nations (UN) Avenue.
Despite the encounter, police have not enforced any arrest.
Some cops were seen removing protesters who were pinned in between the line of cops and the line of demonstrators.
The protesters earlier assembled at Liwasan Bonifacio.
They brought along a truck where they are staging a program.
They seemed to come in batches.
After a first group would fight with the cops, second and third groups would arrive to continue the pressure for them to get past the police barricade.
Most of the militant groups are protesting the visit of United States President Donald Trump.