U.S. cruise operators Royal Caribbean and Carnival said they had "adjusted" their itineraries in the Israel area.
"So far clients haven't been canceling, but they are being more precautious about traveling. We've been getting a lot of inquiries about safety," said Matt Berna, Americas President of Intrepid Travel, a group tour and travel company.
Regulators including the FAA, the European Union Aviation Safety Agency and Israel's aviation authority urged airlines to use caution in the region's airspace, but stopped short of suspending flights.
Russia, though, restricted flights from going to Israel before 0900 GMT due to what it called an "unstable political and military situation" and advised airlines to monitor risks during daylight.
Israel's civil aviation authority asked airlines to "review current security and threat information" and changed some air traffic routes. It noted that delays were expected and advised airlines to carry extra fuel.
U.S. airlines normally run direct services from major cities including New York, Chicago, Washington and Miami.