The distributed denial of service attack against servers hosting sites with a ".cn" domain name began at 2 a.m. Sunday local time, and intensified several hours later, lasting between 2 and 4 hours, the China Internet Network Information Center reported.
DDoS attacks are a common type of hacking attempt in which a target is flooded with traffic to render it unreachable by Internet users. The information center said it would "enhance the service capabilities" of the network serving the affected domains.
Chinese authorities have made no comment as to who they think might be responsible, the BBC reported.
China has been the target of repeated accusations that it is the source of major cyberattacks against Western countries, particularly the United States -- charges China's Foreign Ministry has called groundless.