The Association of Southeast Asian Nations (ASEAN) gathering came a day after the United Nations imposed tough new sanctions on Pyongyang for its nuclear and missile programs and less than a week after Tillerson vowed that the US has no intention of overthrowing the dictatorship of Kim Jong Un.
It claimed the sanctions were caused by a "heinous U.S. plot to isolate and stifle" North Korea and said the country will take "action of justice", but did not elaborate.
Susan Thornton, the top US diplomat for Asia, said Beijing had historically cooperated with sanctions after flagrant North Korean violations but then slipped back over time.
A global pressure campaign on North Korea propelled by sharp new United Nations sanctions received a welcome boost Sunday from China, the North's economic lifeline, as Beijing called on its neighbor to halt its missile and nuclear tests.
"The fundamental reason for THAAD deployment is for our national interest and for the sake of our national security", Tang said, referring to Seoul's Terminal High Altitude Area Defense supplied by the U.S.
There was no direct reaction from North Korea to the remarks but in a statement after the U.S. secretary of state made his comments, Pyongyang responded robustly to the new sanctions by saying it would exact "thousands-fold revenge" on America.
The ASEAN Regional Forum is one of the few multinational gatherings in which North Korea participates.
Speaking at a regional security forum in Manila this week, Mr Wang said the new resolution showed China and the worldwide community's opposition to North Korea's continued missile tests, the foreign ministry said in a statement on Tuesday. He said the North could still carry out further missile tests or a sixth atomic bomb test in the coming months under its broader weapons development timetable.
The sanctions, which target North Korea's foreign currency earnings, ban its exports of coal, coal, iron, iron ore, lead, lead ore and seafood.
The United States, whose Secretary of State, Tillerson, was expected to meet with Duterte on the sidelines of the Manila meetings, had earlier warned that all concerned countries had limited time, and said that the North Korean threat necessitated a strong response.
Analysts say that North Korea, already under numerous United Nations and other global sanctions, will feel some pain from the new sanctions but is not likely to return to disarmament negotiations anytime soon because of them.
Yet another American president is enlisting China to put the squeeze on North Korea. Shin Beomchul of the Seoul-based Korea National Diplomatic Academy said sanctions that can force a change from North Korea would include a ban on China's annual, mostly free shipment of 500,000 tons of crude oil to North Korea and the deporting by United Nations member states of the tens of thousands of North Korean workers now dispatched overseas.
During the ASEAN Regional Forum - the only remaining worldwide forum North Korea sits in outside of the United Nations - the reclusive state aired its side and urged the bloc to be "impartial and practical" in the decades-long standoff.
Tillerson said Washington would not "specify a specific number of days or weeks" before deciding that North Korea had indeed stopped its tests.
Wang did not disclose what Ri had told him during their meeting. Those tests sharply escalated US fears that Pyongyang is a key step closer to mastering the technology needed to strike American soil with a nuclear-tipped missile.
Susan Thornton is the top US diplomat for Asia.