Initial reports had suggested the jet was narrowly missed by debris from a Russian satellite returning to Earth earlier than scheduled.
But US officials said the objects were most likely to have been parts of a disintegrating meteor.
"The object was reported to be uncomfortably close by the pilot"
Airways New Zealand
Ken Mitchell, a spokesman for Airways New Zealand, said while it is not uncommon for debris to fall into the South Pacific "it is very uncommon to have a plane in the middle of it".
"The object was reported to be uncomfortably close by the pilot of the aircraft and we've taken the matter very seriously," he said.
"The pilot estimated the debris to be falling as close as five nautical miles [9.26km] to the aircraft."
Russia's Federal Space Agency issued a statement saying that its cargo ship Progress M-58 had fallen back to Earth according to the timetable it had advised aviation officials about previously.
It said fragments of Progress did not plunge into the South Pacific Ocean east of New Zealand until around 23:30 GMT on Tuesday - about 12 hours after the pilots reported sighting the fiery object.
"Unless someone has their times wrong, there appears to be no correlation,'' Nicholas Johnson, orbital debris chief scientist for NASA's Johnson Space Centre, told The Associated Press.
Johnson said there are no other reports from the US Space Surveillance Network of other re-entering space junk at the time, so the flaming objects must have been fragments of a meteor.