PetroVietnam said two Chinese fishing boats cut across cables being laid by the survey vessel Binh Minh 2 off the coast of central Vietnam on Friday.
"PetroVietnam vehemently protests the Chinese fishing boats' action against the Binh Minh 2," Pham Viet Dung, the deputy head of exploration at the company, said in a statement on the company's website. "We ask that China educate its citizens to respect Vietnamese waters."
Chinese and Vietnamese Foreign Ministry officials had no immediate comment.
China claims most of the South China Sea, bringing it into conflict with its smaller neighbors.
Vietnam, the Philippines, Brunei, Malaysia and Taiwan also claim part of the waters, which are believed to be rich in gas and oil reserves as well as fish stocks. China, which is strengthening its navy, has been increasingly assertive in pressing its claims as its economy as grown in recent years.
It is the second time that Chinese fishing vessels have reportedly damaged the Vietnamese survey ship's cables. An incident in June last year off Vietnam's central coast triggered rare street protests in Hanoi.
It wasn't immediately clear whether the reported incident took place in contested waters. PetroVietnam said it occurred 43 miles (69 kilometers) from the small island of Con Co.
China recently issued new passports featuring a map showing its territorial claims in the South China Sea, angering Vietnam and the Philippines, which have refused to stamp the passports.
Vietnam has also protested a recent announcement by the China National Offshore Oil Corp. opening nine oil and gas lots for international bidders in areas overlapping with existing Vietnamese exploration blocks. Vietnam says the lots lie entirely within its 200-nautical mile exclusive economic zone and continental shelf.