Calling the attack "atrocious", Trump said "nothing's off the table" during a meeting of his Cabinet secretaries on Monday.
The US carried out air strikes previous year after the Syrian regime used a sarin nerve agent in an attack at Khan Sheikhoun that killed 90 people.
Wednesday's statement is also notable because Trump has criticized his predecessors for publicly telegraphing U.S. military action.
In the past, Trump has condemned others for forecasting military plans, repeatedly blistering President Barack Obama during the 2016 campaign.
Asked whether France would take military action, Macron said his country will continue discussing technical and strategic information with USA and British allies and "in the coming days we will announce our decision".
Since then, the regime is alleged to have repeatedly used chlorine and other chemicals, forcing Pentagon planners to consider broader action.
He spoke to British Prime Minister Theresa May over the phone on Tuesday to discuss the crisis.
"It has to happen because it's pretty clear that when it did not happen in 2013, this has basically led to a series of unfolding events where the Assad regime has kept on using chemical weapons against the population", said Fabrice Pothier, Chief Strategy Officer at Rasmussen Global.
On the other hand, Syrian state media and the regime's ally Russian Federation rejected such claims as fabricated.
Horrifying footage made its way around the world this week showing Syrian children being treated, some on the verge of death, after being attacked with chemical gas weapons.
Trump also screeched about how calm things are in the White House, blasting the Michael Cohen raid and the New York Times.
A day earlier, May had said Britain was still assessing who was responsible.
It's believed that any USA military response is unlikely to include significant numbers of ground forces.
U.S. Officials are however urging caution as the administration does not have incontrovertible evidence at hand of the chemical attack as the video evidence has come only through rescue activists on the ground in Syria.
The US Navy launched 59 Tomahawk cruise missiles from destroyers in the eastern Mediterranean, targeting Shayrat air base, its aircraft, ammunition supply bunkers, air defense systems and radars. It's armed with Tomahawk cruise missiles, the weapon of choice in a USA attack one year ago on an airfield in Syria following an alleged sarin gas attack on civilians.
The airspace over Syria is empty and likely will be until at least midday Friday, as the US and its allies contemplate missile strikes in the war-torn country.