They were anxious that the United States intervention in the southern Philippines could worsen the situation, which is still recovering from battle against Islamist militants.
Protesters shout slogans during a protest against US President Donald Trump's visit at the Philippine International Convention Centre in Manila November 11, 2017.
They accused the USA military of committing human rights abuses in Mindanao.
Trump, however, has praised Duterte's "unbelievable job on the drug problem", and told the leader he's "a good man" and should "Keep up the good work".
"Duterte last month declared the liberation of Marawi City from Islamist terrorists after 154 days of fighting, which killed more than 1,100 people, including 165 soldiers, and displaced almost 400,000 residents". "Stabbing. That was when I was 16 years old, just because we just looked at each other".
Addressing the local Filipino community, Duterte said he was not afraid to go to jail, referencing the killing to drive home his point.
Week 11's best top-10 showdown?
It sounds illogical, but the story of the CFP selection committee's second rankings never was going to be the top four (or five). It would also help if nobody among Oklahoma, TCU, Miami and Wisconsin won their conference championship.
Manila and Moscow signed a military deal on logistics, including a contract with a state-owned company for the supply of equipment, during the first-ever visit by a Russian defence minister to the Philippines last month. A person, really. During a fight.
She's been a critic of Duterte's approach to tackling the drug crisis, and denounced the government for carrying out "possible extrajudicial killings" and "a massive, government-led, human rights crisis". A rep for the president, however, tells the AFP the remark was made "in jest", and says Duterte regularly uses "colorful language" when addressing Filipinos overseas, as he was doing while in Da Nang, Vietnam.
In 2016, after noting that Hitler slaughtered millions of Jewish people during the Holocaust, Duterte said: "There are 3 million drug addicts (in the Philippines.) I'd be happy to slaughter them".
Trump headed to Manila later yesterday for the final stop on his marathon Asia tour that has mainly focused on building regional consensus against North Korea's nuclear ambitions and espousing his "America First" vision of global trade.
A bipartisan group of lawmakers, though, were not satisfied with that response.
In a speech that started with his insisting he did not tolerate extrajudicial killings, Duterte apparently switches tack.
"Human rights are fundamental", they wrote.