During the two-hour meeting yesterday afternoon, ministers agreed to join forces with the United States and France to prevent Syrian leader Bashar al-Assad's forces from launching an "appalling and inhumane" attack again.
He did not say whether France is planning military action against Assad's government.
Energy Aspects' Mallinson said Trump's reference to Iran could be viewed as further evidence the USA president is not likely to renew the Iranian nuclear agreement.
According to a statement of the French presidency, Macron calls for dialogue between France and Russian Federation to "continue and intensify" to bring peace and stability to Syria. The Syrian government has denied the allegations.
"The situation in Syria is horrific, the use of chemical weapons is something the world has to prevent", he said.
Trump has claimed that Syrian President Bashar al-Assad's administration has used chemical weapons.
The Kremlin spokesman is warning the USA and its allies against any steps that could destabilize the situation in Syria.
Rep. Adam Smith, the ranking Democrat on the House Armed Services Committee, said he sees no legal justification for a US strike in Syria, absent explicit authorization by Congress. He added that it would have an "utterly destructive impact on the Syrian settlement". That meant airstrikes, possibly in tandem with France and other allies that have expressed outrage at the alleged Syrian chemical attack, could be launched within hours of a presidential decision.
Turkish President Recep Tayyip Erdogan says he will discuss ways of ending "the chemical massacre" in Syria during a telephone call with Russia's President Vladimir Putin.
Later in a White House briefing, Press Secretary Sarah Sanders appeared to walk back the president's words, saying that military options still were being discussed.
Donald Trump denounces James Comey as 'untruthful slime ball'
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"We must increase pressure on Russian Federation to force it to change attitude".
A United Kingdom -based Syrian monitor says that troops have been emptying airports and bases, while opposition fighters have told Sky News Arabia that government-allied forces have been retreating from some positions and moving equipment.
Mr. Mattis said that although the United States has no hard proof, he believes the Syrian government was responsible for Saturday's attack.
Assad said Thursday that Western countries were lashing out after they lost their "bet" on opposition forces in the eastern Ghouta suburbs of the capital.
Assad spoke during a meeting with Ali Akbar Velayati, an aide to Iran's supreme leader. The Lebanese carrier Middle East Airlines has temporarily halted all flights over Syrian airspace, and Kuwait Airlines is suspending all flights landing in Beirut's Rafik Hariri Airport. Israel has said it won't let Iran entrench militarily in Syria, and Prime Minister Benjamin Netanyahu took the occasion of Israel's Holocaust Remembrance Day to warn Tehran not to test his country. British officials said up to 75 people were killed. She is not seeking parliamentary approval for military action but the agreement of the cabinet, which is expected to back a response of non-lethal military assistance to the USA against Syrian targets.
Britain continues to support the US-led coalition targeting IS jihadists in Iraq and Syria, and has conducted more than 1,700 strikes. She has said the use of chemical weapons "cannot go unchallenged".
Britain has been launching air strikes in Syria from its military base in Cyprus, but only against targets linked to the Islamic State militant group.
Britain's Ministry of Defense refused to comment on reports that Royal Navy submarines armed with cruise missiles have been dispatched to within range of Syria.
"I'm not ready to speculate that that would happen", Mr. Mattis said. Moscow, Tehran and Damascus have all denied responsibility for the attack.