"I would support that," Dr. Fauci told The Skimm podcast on Friday. "If you want to get on a plane and travel with other people ... you should be vaccinated."
He did not specify in the podcast interview whether the vaccine mandate he supports would just be for travelers over the age of 12 or all travelers.
The U.S. Travel Association responded that while they support people getting vaccinated, they have "long maintained that there should be no mandatory vaccination requirement for domestic travel."
"Such a policy would have an unfair, negative impact on families with young children who are not yet eligible to get the vaccine," the statement continued.
They believe the mask mandate, which has been extended through January 2022, is enough to keep passengers safe -- pointing to a study conducted by the Department of Defense in partnership with United Airlines.
The study found that the risk of COVID-19 exposure onboard an aircraft is "virtually non-existent" and when masks are worn there is only a 0.003% chance particles from a passenger can enter the breathing space of a passenger sitting beside them.
"Proper tools are already in place to enable safe air travel for Americans," the association emphasized.
White House Coronavirus Response Coordinator Jeff Zients was also asked about the possibility of vaccine mandates for domestic flights Monday.
"We're pulling available levers to require vaccinations and we're not taking any measures off the table," he said.
Last week, the Biden administration proposed employers with more than 100 workers mandate the COVID-19 vaccine or offer weekly testing.
MORE: Delta Air Lines will make unvaccinated employees pay $200 monthly charge
Some major U.S. airlines, like United, have already announced they will require all employees to be fully vaccinated and grant little room for exceptions.
But U.S. airline CEOs have been skeptical about the feasibility of mandating vaccines for passengers.
United CEO Scott Kirby has called the suggestion "logistically impractical."
"I think it would require government response and government tracking to make that practical and make it work," he told MSNBC last month, "and so it's probably unlikely to happen domestically."
Delta CEO Ed Bastian told CBS it would be a "logistical dilemma" to try and implement the requirement in the U.S. and threaten to "bottleneck the domestic travel system."