The retort from Beijing came one day after Vietnam hosted Filipino troops on an island it controls in the disputed Spratlys archipelago in the South China Sea that the Philippines' navy said was designed to "foster camaraderie".
Tensions between China and both countries have risen in recent months over contested territory in the region, with a dispute between Hanoi and Beijing triggering violent anti-Chinese riots in Vietnam last month.
Asked about the joint sports activity, Chinese foreign ministry spokeswoman Hua Chunying said today at a regular briefing: "Don't you think that these small tricks conducted by the Philippines and Vietnam are nothing but a farce?"
The first-ever joint games between the Philippine and Vietnamese navies saw them play football and volleyball and were designed to "foster camaraderie" among the troops, said Philippine Navy spokesman Lieutenant Commander Gregory Fabic.
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"This also serves as a model of cooperation for the other navies to emulate," Fabic added, without mentioning China by name.
The Spratlys are a disputed group of reefs, islands and atolls coveted by the Philippines, Vietnam, China, Malaysia, Brunei and Taiwan.
Tensions between China and Vietnam have escalated sharply in recent weeks following Beijing's dispatch of an oil rig to waters surrounding another contested island group, the Paracels.
Last week, Vietnam released dramatic footage showing a large Chinese ship chasing and ramming one of its fishing boats, which then sank near the rig.
Beijing responded today by issuing a lengthy defence of its use of the rig on both the foreign ministry website and via the official Xinhua news agency.