Air France's precaution comes three years after Malaysia Airlines' MH17 flight was downed by a missile over Ukraine in July 2014...
"Having learned of this missile test we have decided to establish a wider non-flyover zone to move further away from North Korean territory," Air France said in a statement, describing the move as a "precautionary measure".
The airline added: "Information at Air France's disposal at this stage shows the missile fell into the sea more than 100 kilometres from the trajectory" of flight AF293.
The plane with 323 people aboard was flying on July 28 from Tokyo's Haneda airport to Paris' Charles de Gaulle hub and the missile fell into the sea just minutes after the flight passed the area.
"Even if this distance were proven, it would not bring into question the safety of the flight," Air France stated.
A spokesman said the flight concerned passed off without incident.
However, the company, which noted it does not fly over North Korea itself, said it would expand its non-flyover zone as a precaution.
"In cooperation with the authorities, Air France constantly analyses potentially dangerous flyover zones and adapts its flight plans accordingly," the carrier stressed.
North Korea has alarmed the international community with its weapons development programme, and in July conducted two tests of an intercontinental ballistic (ICBM) missile, showing Pyongyang's ICBM capability for the first time.
After last week's second rocket test experts suggested that New York could be in its range.
Air France's precaution comes three years after Malaysia Airlines' MH17 flight was downed by a missile over Ukraine in July 2014, killing 298 people.
Dutch-led investigators concluded that plane was downed by a Russian-made BUK missile transported from Russia into areas held by pro-Moscow rebels.