The confrontation continued after China moved its rig to another location which Vietnam asserted was part of its continental shelf.
Reacting to Vietnam's allegations, Chinese Foreign Ministry spokesman Hong Lei said the Vietnamese vessels rammed into Chinese ships over 1,200 times.
"To be more specific China plays defencive role and Vietnamese the offencive one in relevant waters", he said.
The rig deployment has ruptured carefully nurtured relations between the two Communist countries and caused anti China riots in Vietnam in which four Chinese were killed and over 100 injured.
Unofficial reports said over 20 Chinese were killed in the riots on over 460 foreign factories mostly belonging to Chinese investors.
China, which claims almost all of South China Sea belongs to it, has already evacuated over 7,000 workers from Vietnam.
China says it will not accept international arbitration under UN Convention on Law Seas (UNCLOS) initiated by the Philippines.
The international court in Hague has ordered China to submit its counter-argument by December 15 in the case filed by the Philippines that seeks to resolve the South China Sea dispute.
