Speaking during a visit to the United States on Wednesday, General Guo Boxiong said: "The DPRK [Democratic People's Republic of Korea] is a sovereign state. It has its own assessment of the situation, and its own way of doing business.
"China cannot possibly force the DPRK to do anything or not to do anything.
"However, bearing in mind the peace and stability of the Korean peninsula as well as the goal of denuclearisation of the Korean peninsula, China still tries every means in its power to persuade the DPRK."
Guo is visiting the United States as part of a US-Chinese effort to expand co-operation between their two militaries.
The visit comes two weeks after North Korea launched seven missiles, including a long-range Taepodong-2 missile that the United States said failed in the first minute of flight.
North Korea's missile tests have been largely overshadowed by recent events in the Middle East and little headway has been made toward getting North Korea to return to the talks on its self-announced nuclear weapons production programme.
North Korea has boycotted the negotiations since November.
On Saturday, the UN Security Council passed a resolution criticising the North's missile tests and banning all UN member states from trading with Pyongyang in missile-related technology.
The North has since rejected the resolution.
Six North Korean refugees visited Washington on Wednesday.
Sam Brownback, a Republican senator, urged the world to pay as much attention to human rights violations in North Korea as to the missile launches.
He said: "If we focus only on containing weapons programmes, we will not solve the root of the problem, which is the regime itself."
The refugees, who arrived in May, were the first since George Bush, the US president, signed a law in 2004 meant to make it easier for North Koreans to apply for refugee status.