"When people say, 'Would you direct again?' - I have to be passionate because it's all-consuming, so you have to love it that much," said the screen legend, admitting that making Propeller One-Way Night Coach was at times overwhelming.
However, because of its deeply personal nature - about a young aviation fan who takes a fateful flight to Los Angeles in the golden age of flying in the 1950s and 1960s - he could handle it, he said.
"It was me being overwhelmed with the things I love and my family and my friends," Travolta, an experienced pilot, said at the festival.
Travolta cast several of his relatives, including his daughter, Ella Bleu Travolta, who said watching her experienced family members work on set "felt like a master class."
Travolta, produced, financed, directed, narrated and wrote the film based on a book he published some three decades ago.
The star of hits such as Pulp Fiction and Grease was surprised with an honorary Palme d'Or prize on Friday ahead of the premiere, becoming visibly emotional as he accepted the award that he said was more important to him than an Oscar.
Propeller, which was shown outside the competition section, will be released on Apple TV on May 29.
Critics praised the film with an hour-long run time as endearing if a bit odd, with The Guardian's critic calling it "a rather charmingly quirky and distinctively peculiar novella-sized bedtime story."
