Security allies Washington and Tokyo expressed "deep concern" over Beijing's new Air Defence Identification Zone (ADIZ), which both called a unilateral attempt to change the status quo in the East China Sea.
The zone that China declared on Nov 23 dominated talks between visiting US Vice-President Joe Biden and Japan's Prime Minister Shinzo Abe here on Tuesday.
At a joint press conference after the meeting, Mr Abe again called for the ADIZ to be scrapped.
"We will not remain silent at the unilateral move by China to change the status quo by force. Under our strong Japan-US alliance, we will work closely to deal with the issue," he said.
Mr Biden said the US is deeply concerned about China's action, which "has raised regional tensions and increased the risk of accidents and miscalculation".
"This underscores the need for crisis management mechanisms and effective channels of communication between China and Japan to reduce risk of escalation," he said.
Mr Biden made it clear the US would stand by Japan when he said: "We will remain steadfast in our alliance's commitment."
China requires foreign planes to file their flight plans before flying through its ADIZ, and warns of "defensive emergency measures" if they do not cooperate.
Japan's two largest airlines complied, but stopped after the government told them not to.
The US Federal Aviation Administration, however, reminded US airlines to comply with requests by foreign governments.
Earlier in Washington, State Department spokesman Jen Psaki said China should rescind confusing ADIZ procedures that have raised the risk of accidents.