The suspension comes shortly after US President Donald Trump visited Beijing and pressed his counterpart Xi Jinping to do more to rein in North Korea's nuclear program.
China sent a special envoy, Song Tao, to the North last week but his four-day trip ended with no direct statement on the crisis, after Pyongyang's series of nuclear and missile tests triggered global alarm.
Air China said in a statement to AFP that it cancelled the Beijing to Pyongyang flight route because the "operational situation is not ideal".
"Market conditions will determine the resumption of the flight route," the statement said.
Air China last cancelled flights to North Korea in April, citing low customer demand, but resumed them soon after.
China has denied any political motives behind its flag carrier's suspension of the route.
"The airliners just work out their own operation plans based on the state of operation and the market," foreign ministry spokesman Lu Kang said at a press briefing on Tuesday when asked about the apparent move.
Passengers flying from Beijing to North Korea are now left with just three regularly scheduled flights each week, on the North Korean state airline Air Koryo.
Air Koryo also operates flights from the northeastern Chinese city of Shenyang to Pyongyang, though it halted flights from the Chinese border city of Dandong earlier this year.
Beijing is Pyongyang's only major ally and biggest trade partner, though in August China said it would abide by new UN sanctions which heavily curtail the North's exports of its most profitable goods.
The US on Tuesday unveiled new sanctions targeting North Korean shipping and Chinese traders doing business with Pyongyang, again raising the pressure on the pariah state to abandon its nuclear program.
China's foreign ministry rejected the sanctions on Chinese firms as "wrong", stressing that Beijing has enforced UN measures curbing trade with Pyongyang.
(AFP World News)