The assembly said in a statement the decision by state-run China National Offshore Oil Corp. to deploy rig HD-981 about 120 miles off the coast of Vietnam is a serious violation of its sovereignty and international laws.
"The National Assembly shows its concern and resolutely protests China's violation and wrongdoing and demands that China withdraw the oil rig out of Vietnamese waters," it said.
Both sides have made claims to the maritime territory near the Paracel Islands in the South China Sea. The U.S. government has weighed in saying that, while it has no stance on sovereign claims, China's behavior has been provocative.
Beijing last week evacuated some of its nationals after anti-Chinese riots in Vietnam turned violent. More than 140 people were injured during the demonstrations.
China is at odds with most of its neighbors in the Asia-Pacific over claims to the maritime territory.
Vietnamese Deputy Prime Minister Pham Binh Minh in early May said the Chinese rig deployment was a national security concern. Hanoi, he said, reserves the right to take "all the proper and necessary measures to protect its legitimate rights" in the region.