Carrying placards declaring "Dump Trump" and "Down with U.S. Imperialism", the left-wing protesters were blocked by police in riot gear with shields and batons, and then showered with jets of water from a fire engine.
The rally was part of the series of "Ban Trump" protests, as Bayan denounced the holding of the 31st summit of the Association of South East Asian Nations (ASEAN) and US President Trump.
Philippine President Rodrigo Duterte will host world leaders in Manila from Sunday, hoping their presence will quieten global criticism over his deadly drugs war, which rights groups say may be a crime against humanity.
Hosted by President Rodrigo Duterte, the dinner at the SMX Convention Center marks the beginning of the three-day Summits where leaders from 20 countries, European Union and United Nations are converging in the capital for their annual gathering.
The summit of Asia-Pacific Economic Cooperation (APEC) countries in Vietnam put on show the contrasting vision of the "America First" policy with the traditional consensus favouring multinational deals that China now seeks to champion. He added that he is "a very good mediator and arbitrator".
"If I can help mediate or arbitrate, please let me know", Trump said at a meeting in Hanoi with his Vietnamese counterpart, Tran Dai Quang.
"I just wanted to congratulate you because I am hearing of the unbelievable job on the drug problem", Trump said, not mentioning the thousands killed and worldwide scorn.More news: Four-star Hamilton on record pace in Brazil
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"Unbridled, undisturbed, unmolested while we use that small way from the Indian Ocean. facing Palawan", Duterte said, referencing the southern Philippines province which juts out into the South China Sea.
"The two sides returned to the track of appropriately handling the South China Sea issue through dialogue and consultation, thus removing the stumbling block that has held back our bilateral relations for several years", Li said.
Trump's Asian tour comes as the USA rallies for tougher sanctions against North Korea's nuclear program and ballistic missile tests.
China claims nearly the entire South China Sea, with competing claims from Taiwan, Vietnam, the Philippines, Malaysia and Brunei.
The United States has criticized China's construction of islands and its build-up of military facilities in the sea, and is concerned they could be used to restrict free nautical movement. The South China Sea will likely be a hot topic throughout the summit, as most claimants will be attending. The country claims a huge swathe of the South China Sea.
With China's provocative actions in the South China Sea, Roque said the issue is expected to be discussed by the two leaders.