Foreign Ministry spokesman Hong Lei said the summer moratorium was an annual event and that China was merely fulfilling its international responsibilities and obligations to conserve fish stocks. "China's position on the South China Sea is consistent and clear," Hong told reporters.
Vietnam had issued a statement late Saturday criticising the ban as a "worthless decision" and reasserting Vietnam's claim to the disputed Paracel Islands and their surrounding waters.
Tensions spiked a year ago when China parked a giant oil rig near the islands. Anti-China demonstrations in Vietnam left at least four Chinese dead, while ships from the sides sparred in the waters surrounding the rig.
Despite its tough talk, the government in Hanoi has limited options, considering Beijing's massive military and huge financial resources. Vietnamese officials are believed to be split between a faction that favors a tough line against Beijing and stronger ties with the US and one that favors a quiet compromise with China.
China has faced growing criticism over its island reclamation drive, with frictions over the issue clouding a visit to Beijing by US Secretary of State John Kerry over the weekend.