"The global political situation has become very serious due to North Korea's repeated provocations," the South Korean leader told the Russian president as the two held a bilateral summit here in the far eastern Russian city of Vladivostok.
"I believe the situation may enter an uncontrollable state if the North does not halt its provocations. So I wish to work together to have North Korea stop its provocations and find ways to fundamentally resolve the North Korean nuclear issue," Moon added, Yonhap news agency reported.
The Moon-Putin summit came amid growing concerns over North Korea's apparently evolving nuclear and missile capabilities.
Pyongyang conducted its sixth and what many believe to be its most powerful nuclear test so far Sunday. The communist state has also staged nine missile tests since the new South Korean leader took office in May. Since the beginning of the year, the communist regime has conducted 14 missile launches.
In his earlier telephone conversation with Putin, held one day after the North's latest nuclear provocation, the South Korean leader stressed the need to put in place additional and stronger sanctions against the North that will leave the country with no other choice but to come to the dialogue table.
Such measures should include completely cutting off the oil supply to the impoverished North, Moon has said.
Putin was reluctant to give any immediate response, saying they should talk more when they meet in Vladivostok this week, according to Seoul's presidential office Cheong Wa Dae.
At the start of his meeting with Moon, the Russian president said he looked forward to discussing various issues, including the North Korean nuclear and missile issues that "we think are concerning."
Following their bilateral summit, Moon and Putin will be joined by more than a dozen top government officials from each side for what Cheong Wa Dae called an expanded summit.
The two leaders will hold a joint press conference on the outcome of their summit.
Moon arrived earlier in the day for a two-day visit. He was set to hold a bilateral summit with his Mongolian counterpart Khaltmaagiin Battulga later Wednesday.
On Thursday, the South Korean president will hold bilateral talks with Japanese Prime Minister Shinzo Abe before attending the third Eastern Economic Forum, an economic summit aimed at promoting regional cooperation in the development of the Russian Far East.