ALSO READTrump says he wants US troops 'out' of Syria After stopping aid for Pakistan, Trump threatens same action against Palestinians China vows to respond to US tariffs with 'necessary measures' Trump says tariffs will be 'very fair,' names winners and losers Trump says to meet Syria advisors, decision 'fairly soon'
Russia, Syria's main military ally, strongly opposes such action.
"The immediate priority is to avert the danger of war," he told reporters.
The UN Security Council is to hold an emergency meeting later to discuss the crisis.
On Sunday, the day after the attack, the US President said Russian President Vladimir Putin bore responsibility for the "atrocity" in rebel-held Douma, because of his support for the Syrian government.
Trump, who has cancelled a planned trip abroad, has been canvassing support for strikes from the leaders of France and the UK.
On Wednesday, he said the missiles were "coming", but on Thursday he tweeted that he had "never said when". It "could be very soon or not so soon at all", he said.
He later told reporters at the White House: "We're having a meeting today on Syria... We have to make some further decisions. So they'll be made fairly soon."
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)