It concludes that there is "no plausible scenario other than that of an attack by Syrian armed forces".
Meanwhile, May said the missile strike, created to minimise civilian casualties, was aimed at deterring further use of chemical weapons and was not an attempt to topple the Syrian government.
Khamenei said on Twitter early Saturday the US and its allies were committing a crime.
Russia's ambassador to the United States Anatoly Antonov said in response to precision air strikes by the U.S., France and Britain in Syria Saturday that "All the responsibility for these consequences will fall on Washington, London and Paris".
The U.S., France and Britain launched airstrikes against Syria's capital Damascus before daybreak on Saturday, with loud explosions heard and red dots seen flying into the sky, according to Syrian state TV and Xinhua reporters in Damascus.
It also repeats the claims made by Russian officials that a majority of the missiles launched by the U.S. had been intercepted.
Iranian Drone Introduced By Syria Israel States
"The Syrian nation will continue to resist against foreign aggression.Iran has always helped and will continue to support oppressed nations in the region and around the globe", Rouhani said. There has always been a question about Israel treading the fine line between Russian Federation and Iran in Syria, but there is now the added complication of treading the line between Russian Federation and the U.S.as well, and in a strategic environment where the USA has been unwilling to back Israeli objectives.
"The interception of the Iranian unmanned aircraft by an attack helicopter prevented an Iranian intent to carry out an attack in the territory of the State of Israel", read a statement by the army. Following the strike and the questions over its provenance, Israel maintained its customary silence, but was quickly fingered first by Russian Federation and then by the U.S.as the party responsible.
May authorized the strikes without a vote from Parliament, which has been in recess.
The Syrian government's staunch allies strongly condemned the overnight airstrikes on Assad regime targets, with Iran's supreme leader branding as "criminals" President Donald Trump, U.K. Prime Minister Theresa May and French President Emmanuel Macron.
The Syrian government has repeatedly denied any use of banned weapons. Syrians crowded onto the streets in noisy demonstrations of defiance afterward and their ally Russian Federation denounced the attack.
After the chemical gas attack by the Assad regime on civilians in Douma, an airstrike took place on the T4 air base in Syria. Defense Secretary Jim Mattis said there were no reports of US losses in what he described as a heavy but carefully limited assault.