He said Britain had told the White Helmets, who act as first responders in rebel-held areas, to fake the suspected chemical attack in the town of Douma.
"After midnight, 85 buses left Eastern Ghouta carrying 4,000 people, both fighters and civilians", the Syrian Observatory for Human Rights monitoring organisation said. He didn't elaborate or name the state.
It comes as London has blamed Moscow for a nerve agent attack on a former double agent and his daughter in the English city of Salisbury last month.
The Russian leader warned against "ill-considered and unsafe actions ... that would have consequences beyond conjecture". Putin and Macron instructed their foreign and defence ministers to maintain close contact to "de-escalate the situation", the Kremlin said.
She told an emergency meeting of the U.N. Security Council called by Russian Federation that should the US and its allies decide to act in Syria it will be to defend "a bedrock worldwide norm that benefits all nations" - the prohibition on the use of chemical weapons. He said "the Cold War is back - with a vengeance but with a difference", because safeguards that managed the risk of escalation in the past "no longer seem to be present".
President Bashar al-Assad's government - which receives military backing from Russian Federation - denies any involvement and says reports of a chemical attack are "fabricated". She said of the alleged chemical attack that "Russia can complain all it wants about fake news, but no one is buying its lies and its coverups".
He added without elaboration that Moscow has "irrefutable information that it was another fabrication". "We hope there will be no point of no return", the envoy said.
Similarly, French President Emmanuel Macron said he had "proof" that the Syrian government had attacked Douma with chemical weapons, without giving further details.
The victims of the April 7 incident were mostly women and children, activists told Al Jazeera from Eastern Ghouta, a Damascus suburb.
The ministry also pointed at previous use of chemicals by rebels in fighting with Syrian government troops.
Sergey Lavrov did not specify which agency or provide evidence, but he warned the West against proposed military action. About 2,000 USA military personnel are in Syria.
Russian Federation has been involved in the Syrian conflict since 2015 and became Syrian President Bashar al-Assad's main ally in the war against armed opposition groups. Syria's civil war, which began as a popular uprising against Assad, is now in its eighth year.
Later, May's office said she had spoken with Trump by telephone, and the two had agreed it was vital to challenge Assad's use of chemical weapons, and that they would continue to work closely together to do so. The officials said they were "confident" in the intelligence, though not 100 percent sure.
"The evacuation operation should wrap up before the OPCW experts enter Douma", Abdel Rahman said.
"Today a significant event in the history of Syria took place".
The Russian military announced on Thursday that the Syrian government is now in full control of the town on the outskirts of Damascus that was held by the rebels and that was the site of a suspected chemical attack over the weekend.
With Russian military assistance, al-Assad launched a military offensive on Eastern Ghouta, which had been under rebel control since mid-2013.