It is one of the very few multilateral events attended by North Korea's foreign minister nearly every year.
Bolivar also said that the two countries were able to discuss the future direction of their partnership during the meeting.
During the Park Geun-hye administration, both North and South Korean foreign ministers attended the forum but did not engage in talks.
After arriving in the Philippine capital, Kono, who assumed his post Thursday in a Cabinet reshuffle, met with the foreign ministers of the Association of Southeast Asian Nations.
Southeast Asia's top diplomats will meet with with their counterparts from the bloc's 17 dialogue partner states Monday afternoon at the ASEAN Regional Forum, a key security summit where representatives of the suspended six party talks - North Korea, South Korea, Japan, China, Russia, and the United States - are expected to have a heated discussion on the imposition of sanctions against Pyongyang.
The three ministers will share their assessments of North Korea's repeated strategic provocations and discuss responses, the ministry said.
MOFA told media in late July that Seoul didn't "have any detailed plan to hold foreign ministerial talks between the South and the North on a specific occasion", after Ri's attendance was confirmed by the Philippine government.
This is the first time that high-ranking South Korean and North Korean government officials are reported to have spoken since the inauguration of Moon Jae-in on May 10. In a bilateral meeting with Ri on Sunday, Chinese Foreign Minister Wang Yi called for Pyongyang to stop nuclear and missile tests.
The Philippines is chair of the ASEAN this year.
Japan has been mired in a territorial dispute with China over the Senkaku Islands in the East China Sea, a group of uninhabited islets controlled by Japan and claimed by Beijing, which calls the islands Diaoyu. The U.S. has been pushing to temporarily expel Pyongyang from the 27-member Association of Southeast Asian Nations Regional Forum, but diplomats gathered here have been split on that proposal.
Tokyo will "closely" cooperate with the ASEAN countries, China and South Korea "in order to increase the predictability of a regional or world economic crisis", Japan's new foreign minister, Taro Kono, said during the meeting in Manila.
Ahead of Tillerson's trip, the top American diplomat for Asia said the US was expecting a "general chorus of condemnation of North Korea's provocative behavior" as well as "pretty serious diplomatic isolation directed at the North Korean foreign minister". The Russian delegation to the events is led by Foreign Minister Sergey Lavrov.