The decision was made Thursday, according to a government statement released later the same day.
Vietnam and China have sparred for years over who owns what in the South China Sea but tensions escalated sharply in early May when Beijing deployed a large oil rig near the disputed Paracel islands.
Hanoi protested the deployment and has sent coastal patrol ships to try and shoo away the rig, which is protected by a large flotilla of Chinese ships. The ships have been unable to get close to the rig, and several have been damaged in collisions with larger, stronger Chinese vessels.
The Vietnam government says it hasn't deployed navy vessels anywhere near the rig.