Seoul and Tokyo, along with Washington, which is in security alliances with them both, have all refused to accept Beijing's air defence identification zone (ADIZ).
The Chinese ADIZ overlaps with both Japan and South Korea's, which were set up decades ago, and includes areas claimed by both countries.
Beijing has lashed out at historic rival Tokyo, with which it is embroiled in a row over islands in the East China Sea that has escalated since last year.
At a regular press briefing foreign ministry spokesman Hong Lei expressed regret over Seoul's announcement yesterday that it was expanding its ADIZ by about 66,480 square kilometres (25,670 square miles) -- roughly two thirds the size of the country.
More From This Section
"China expresses regret over the ROK's decision to expand its ADIZ," he said, referring to the formal name Republic of Korea.
"China will stay in communication with the ROK based on equality and mutual respect. We hope that the ROK will meet China halfway," he continued.
China's state-run media downplayed the issue, with the Chinese-language edition of the Global Times, which normally strikes a nationalist tone, saying in an editorial: "China will not make a big deal out of this right now."
South Korea's move to extend its air zone -- the first revision to its air defence area for 62 years -- was "opportunistic" in light of the more serious standoff between Beijing and Tokyo, it said, but added that "China respects Korea's interests".
No editorials on the subject appeared in other major outlets, including the ruling Communist Party paper, the People's Daily, or the state news agency Xinhua, while reports on the news were mild.