Dunford also said on Thursday that the US and South Korea would go ahead with joint military drills next week despite opposition from both China and North Korea.
The chairman of the U.S. Joint Chiefs of Staff made a visit to China's border with North Korea on Wednesday.
Military action is not an option in resolving the North Korean nuclear crisis, a senior Chinese army official told his U.S. counterpart on Thursday.
Asked to respond to the criticism that China's "dual suspension" proposal to halt the US military drills with South Korea and the North's missile tests made a false equivalence between the two, Foreign Ministry Spokeswoman Hua Chunying said it was the most realistic and achievable solution.
Joseph Dunford, chairman of the Joint Chiefs of Staff (JCS), a body of uniformed leaders in the U.S. Department of Defense, kicked off his visit to China on Tuesday for further military-to-military cooperation between the two countries.
China's Defense Ministry said the two officials also discussed Taiwan and North Korea-related issues, but did not go into details.
The South Korean leader also said North Korea's development of nuclear weapons technology was "nearing" a red line, which he described as "completing an ICBM and weaponizing it with a nuclear head".
The top United States general repeated Washington's "ironclad commitment" to the security of its close Asian ally, Japan, on Friday amid regional tensions over North Korea, telling his counterpart in Tokyo that "an attack on one is an attack on both of us". But fears of conflict remain as the US and South Korea next week begin military drills that the North views as preparation for invasion, and as Washington seeks to stop the North's progress toward having a nuclear-tipped missile that could strike the continental United States.
"Against North Korea, even with extreme pressure, it has to be solved peacefully and our opinion and U.S. opinion about this matter is not different", Moon said. Kim appeared in photos sitting at a table with a large map marked by a straight line between what appeared to be northeastern North Korea and Guam, and passing over Japan - apparently showing the missiles' flight route.
Earlier, Dunford met with his Chinese counterpart Fang Fenghui in Beijing and agreed to bolster military cooperation.
China is North Korea's main economic partner and political backer, although relations between Beijing and Pyongyang have deteriorated amid the North's continuing defiance of China's calls for restraint.
Tensions have risen after North Korea conducted two missile tests in July which, like its five atomic bomb tests, were carried out in defiance of global pressure and United Nations resolutions.
Tokyo remains on alert against potential military provocations by Pyongyang after North Korea threatened to fire missiles towards the Pacific island of Guam, US territory, which would have flown over Japan. North Korea has fired missiles and taken other steps in response to the war games in the past.
Guam is a US island territory and hosts two USA military bases.