"As the international community awaits the International Tribunal on the Law of the Sea's decision regarding China's excessive maritime claims to the South China Sea, we are also concerned by Beijing's recent action to unilaterally raise tensions in the East China Sea," four top Senators said in a statement.
The statement was jointly signed by Senators John McCain and Jack Reed, Chairman and Ranking Member of the Senate Armed Services Committee, and Bob Corker and Ben Cardin, Chairman and Ranking Member of the Senate Foreign Relations Committee.
China and Japan both claim a small group of islands in the East China Sea, known as Senkaku in Japanese and Diaoyu in Chinese.
China established an air-defense identification zone (ADIZ) over the East China Sea in 2013, raising protests from the US and several Asian countries. The US responded by sending two B-52 bombers inside the zone without notifying Chinese authorities.
The US said Chinese fighter jets made an "unsafe" interception of a reconnaissance flight in international airspace over the East China Sea earlier this month.
Tensions have renewed in the East China Sea after Japan used the G7 meetings to criticise China and express opposition to any "intimidating, coercive or provocative" actions in both the East and South China seas, drawing an angry reaction from Beijing.