US President Donald Trump cited a failure to reach an agreement to limit Iran’s nuclear programme and regime change as among the reasons for launching the attack.
Iranian airspace has been closed and flight tracking shows international air traffic avoiding the region.
British Airways has cancelled services to Tel Aviv and Bahrain until Wednesday, and Amman in Jordan on Saturday.
Passengers on the 20:00 flight to Doha on Friday returned to Heathrow after it turned back part way through the journey, but this was due to a technical issue with the aircraft and unrelated to the military action.
Sarah Short was due to return from a holiday in Dubai to Heathrow on Saturday.
“We got on the plane and were literally about to taxi when the pilot said: ‘We have some bad news – we’re not going anywhere’,” she told the BBC. “We then sat on the plane on the tarmac for over three hours.”
She added: “There’s no flights, everything’s suspended. BA said there’s nothing they can do,” she said. “It’s all so volatile, you just don’t know what’s going to happen next.”
Virgin Atlantic cancelled a Heathrow to Dubai flight and warned its flights to India, Saudi Arabia and the Maldives may take longer due to being rerouted.
Wizz Air suspended all flights to and from Israel, Dubai, Abu Dhabi and Amman up until and including next Saturday.
Qatar Airways confirmed the temporary suspension of flights to and from its capital Doha due to the closure of Qatari airspace, while Emirates said it was temporarily stopping services to and from Dubai.
Heathrow, the UK’s busiest airport, urged travellers to check with their airline for updates.