The Group of Seven industrialized nations said it is "deeply concerned" about tensions in the East and South China Sea, where Beijing is involved in territorial disputes with its neighbors.
In a statement released after meeting Wednesday in Brussels, G7 leaders said they oppose unilateral attempts to assert territorial or maritime claims through use of intimidation, coercion or force.
Though the statement did not mention any individual country, it is seen as a criticism of China, whose neighbors accuse it of using bullying tactics to advance its wide-ranging maritime claims.
China and Japan both claim territory in the East China Sea. The dispute worsened in 2012 after Japan nationalized a group of islands there. Beijing has since declared an Air Defense Identification Zone in the area.
In the South China Sea, Beijing is involved in a tense standoff with Vietnam over a state-run Chinese oil rig that was placed in disputed waters off Hanoi's coast. Both countries' ships have exchanged water cannon fire and rammed each other.
China's claims in the South China Sea also overlap with those of the Philippines, Malaysia, Brunei, and Taiwan.
The United States has said it does not take a position in the disputes, but has strongly criticized China's actions. Defense Secretary Chuck Hagel recently called Beijing's moves "destabilizing."
Beijing rejects such statements as foreign interference in its affairs. It has not commented on the G7 statement.