"The time has come for the South, the North and the United States to focus together on the soonest convening of working negotiations between North Korea and the United States," Moon said in a speech timed with the National Liberation Day of Korea.
Moon noted there were some "unpleasant moments", saying they should not impede the talks, because all problems should be addressed at the negotiating table.
The president argued that despite "some concerning actions" by Pyongyang, the denuclearization dialogue should bring significant results on removing nuclear weapons from the Korean Peninsula.
Moon also noted recent positive changes in peninsula stability.
Moon's speech was broadcast live by the local YTN TV channel.
North Korea's leader, Kim Jong Un, and US President Donald Trump agreed to resume working consultations on the denuclearization as they met in the Korean Demilitarized Zone in late June. The talks previously reached a deadlock after two rounds resulted in the lack of agreement.
Notably, since late July, Pyongyang carried out a number of weapons tests, which Seoul called launches of short-range ballistic missiles. North Korea is prohibited from developing its ballistic missile program by UNSC resolutions. Trump downplayed the launches, saying that other countries tested the same missiles.