At the end of the summit in Germany, which starts on June 7, members will release a declaration calling for maintaining an international order of seas based on international law, the report said, without citing sources. No country will be singled out.
G7 leaders a year ago expressed their concern about tensions between China and a number of other Asian countries over resources in the East Vietnam Sea and East China Sea, and warned against any use of force.
China claims most of the East Vietnam Sea, through which US$5 trillion in ship-borne trade passes every year. The Philippines, Brunei, Malaysia, Taiwan and Vietnam also have overlapping claims.
All but Brunei have fortified bases in the disputed waters, which are roughly 1,300 km (800 miles) from the Chinese mainland but much closer to the Southeast Asian claimants.
Japan also has a territorial row with China over islands in the East China Sea.
China has been criticised for extensive reclamation work and moves to turn submerged rocks into man-made structures. The United States last week said Beijing had placed mobile artillery systems in contested territory.
