"The improvement of relations between North and South Korea cannot go separately with resolving North Korea's nuclear programme, so the foreign ministry should coordinate closely with allies and the international community regarding this," Moon said in opening remarks at a cabinet meeting on Tuesday.
Moon's comments contrasted with those of North Korean leader Kim Jong Un, who said on Monday that Seoul should stop asking foreign countries for help in improving ties between the two Koreas.
"This shows the Moon administration is looking at the situation from a very realistic, rational point of view," said Jeong Yeung-tae, head of the Institute of North Korea Studies in Seoul.
"It also shows resolving North Korea's nuclear issue has a bigger priority (than improving inter-Korean relations)."
Moon's comments came after a New Year's Day speech by Kim who said he was "open to dialogue" with Seoul, and for North Korean athletes to possibly take part in the Winter Games, but steadfastly declared North Korea a nuclear power.
The South Korean president requested the ministries of unification and sports to swiftly create measures to help North Korea participate in the upcoming Pyeongchang Winter Olympics.
As for talks between the two Koreas, Defence Ministry spokeswoman Choi Hyun-soo says Seoul is awaiting a more detailed reply from Pyongyang to already-existing offers for dialogue made back in July last year by Seoul.
"We offered military talks in July and our offer still stands. We are waiting North Korea's reply. We are willing to talk with North Korea on the peaceful resolution of the North's nuclear programme regardless of form, time and method," Choi said in a regular briefing.
Kim's offer of talks and sporting co-operation with South Korea follows a year dominated by fiery rhetoric and escalating tensions over Pyongyang's nuclear weapons programme.
North Korea tested its most powerful intercontinental ballistic missile (ICBM) in November, which it said was capable of delivering a warhead to anywhere in the United States.
On Monday, Kim said the North would mass produce nuclear warheads and ballistic missiles in 2018 for operational deployment, warning he had a "nuclear button" on his desk which he would use if his country was threatened.
