The medics said none of the patients were hurt by chemicals.
Trump met with members of his National Security Council on Thursday to discuss the US's options with regards to Syria.
Now, the question has become: Has the clock run out on an effective response to the attack? Russia is a growing military power, but it is a global actor losing blood in terms of the economy.
He said: "It's too bad that the world puts us in a position like that, but as I said this morning we've done a great job with ISIS".
On Monday, Mr. Trump said a decision on how to respond to the attacks would come in "24 to 48" hours.
The Russian leader warned against "ill-considered and dangerous actions ... that would have consequences beyond conjecture".
Macron's office and the French military aren't commenting on pending plans.
In a further sign that military action may be imminent, Eurocontrol, the European air-traffic control agency, issued a warning on Wednesday to commercial airliners flying in the eastern Mediterranean.
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There is a heightened "danger of escalation" because of the Russian military presence in Syria, Nebenzia said after a private meeting of the UN Security Council in New York.
"We warned about this long ago", he said. "Nine people reportedly died in last year's attack, including four children".
At another hearing, General Mark Milley, the US Army's chief of staff, agreed with Mr Trump that Assad should pay a big price.
Macron doesn't need parliamentary permission to launch an operation.
Ziad Majed, political scientist at the American University of Paris, said: "If the strikes are large-scale and the Russians understand that the West is steadfast. there may be a political dynamic to find a compromise".
Russia has been a staunch ally of Syrian President Bashar Assad's government and has helped turn the tide of war in his favor since entering the conflict in September 2015. And he insisted it remains US policy not to be involved directly in Syria's civil war.
Russia, Iran, Turkey and the United States are all pursuing their own agendas in Syria.
Asked about possible U.S. strikes on Syria, President Vladimir Putin's spokesman Dmitry Peskov said Thursday that "it's necessary to avoid any steps that may fuel tensions in Syria".