"It was very chaotic, you know, people were in disarray and running everywhere," Dr Tedros said on Saturday.
He added there was "no shelter, so we were completely exposed. It's a matter of luck, otherwise if the missile deviated just slightly it could have been on our heads".
"So my colleague actually said, after all that, we escaped death narrowly," he said.
The WHO chief - who has led the organisation since 2017 and made regular public appearances during the Covid pandemic - said his presence at the airport was public knowledge prior to the strike.
But he added: "It doesn't matter whether I'm there or not. Any civilian life is life - my life is not better than another human being."
Dr Tedros said the airport is a civilian facility and therefore should not have been attacked by Israel.