China has said it will not resort to the use of force to resolve maritime border disputes in the South China Sea.
Several Asian nations claim territory in the South China Sea, which includes important shipping routes and may contain oil and gas deposits.
On Monday, Vietnam staged live-fire drills after weeks of rising tensions between the two nations.
Vietnam has also issued a decree specifying who would be exempt from military call-up in a time of war.
"We will not resort to the use of force or the threat of force," Chinese foreign ministry spokesman Hong Lei said.
He condemned any action that would exacerbate the dispute, and urged those involved to "do more that is beneficial to regional peace and stability".
As well as Vietnam, the Philippines, Malaysia, Brunei and Taiwan also have rival claims in the area.
As chair of the regional grouping Asean last year, Hanoi actively promoted a multilateral approach to the problem. However, Beijing says it prefers to negotiate with individual states separately.
In an apparent message to China that Vietnam is willing to stand its ground, the Vietnamese government issued a decree earlier specifying which people would be exempt from military service during a time of war.
The decree lists eight examples where Vietnamese citizens would not be obliged to join a military call-up. They include people holding senior positions in state organisations and those providing essential services such as lighthouse operators.
The BBC's South East Asia correspondent Rachel Harvey says the significance lies not in the exemptions themselves but in the timing of the decree.
The news comes a day after the Vietnamese navy conducted exercises it described as routine, but which at least one Chinese newspaper interpreted as a deliberate show of force.
Vietnam is engaged in a renewed row with China over sovereignty of two groups of islands in the South China Sea; the Spratly and Paracel islands.
Tensions have escalated following two separate confrontations involving Vietnamese and Chinese boats in recent weeks.
In a thinly veiled reference to Hanoi, Mr Hong implied Vietnam was to blame for the recent row.
"Some country took unilateral actions to impair China's sovereignty and maritime rights and interests, and released groundless and irresponsible remarks with the attempt to expand and complicate the issue of the South China Seas," Mr Hong said.
"This is where the problem lies."
The US has also expressed concern about China's rising naval ambitions in the region.
On Sunday, the Japan-based carrier USS George Washington left port for deployment in the region, which is almost certain to include the South China Sea.