Muslims from seven countries were barred Saturday from flying to the US and others detained there after President Donald Trump froze arrivals, with one man saying his life has been "destroyed".
Photo from video
Trump on Friday signed a sweeping executive order to suspend the arrival of refugees and impose tough new controls on travellers from Iran, Iraq, Libya, Somalia, Syria and Yemen.
His move sparked widespread international criticism and personal heartache.
Iran, which saw many of its citizens stranded in European and Middle Eastern airports, denounced the "insulting" ban and said it would reciprocate.
Airlines said they had no choice but to respect Trump's executive order and deny citizens from the seven Muslim-majority countries from travelling to the US.
Two travel agencies in Iran said they had been instructed by Etihad Airways, Emirates and Turkish Airlines not to sell US tickets or allow Iranians holding American visas to board US-bound flights.
There are no flights from Iran to the United States, where more than a million Iranians live.
Iranian President Hassan Rouhani did not comment directly on the ban Saturday, but said that now was "not the time to build walls between nations".
The Islamic republic's foreign ministry said it would "respond in kind after the insulting decision of the United States concerning Iranian nationals" until the measure is lifted.
Tehran called the decision "illegal, illogical and contrary to international rules".
In Khartoum, the Sudanese foreign ministry expressed its "regret" at the US ban.
On Saturday, the American Civil Liberties Union and other advocacy groups filed a legal challenge to Trump's order, and asked for their suit to be considered a class action.
The United Nations urged Trump to continue his country's "long tradition" of welcoming refugees and to ensure their equal treatment, regardless of race, nationality or religion.
French President Francois Hollande said Europe must have a "firm response" to Trump, and "when he refuses the arrival of refugees, while Europe has done its duty, we have to respond".
Trump's decree -- which he says aims to make America safe from "radical Islamic terrorists" -- specifically says no visas will be issued for 90 days to migrants or visitors from the seven Muslim states.
It also bars Syrian refugees indefinitely, or until Trump himself decides that they no longer pose a threat.
His decree suspends the entire US refugee resettlement programme for at least 120 days while tough new vetting rules are established.
