Mr Raab said: "We are now confident that Iran was responsible" (Picture: PA).
The UK Government "carefully and independently" came to the conclusion that Iran was responsible for missile strikes on a Saudi oil plant, Foreign Secretary Dominic Raab has said.
Mr Raab reiterated the position Prime Minister Boris Johnson outlined during his flight to the United Nations General Assembly in New York on Monday.
In a statement, Mr Raab told the Commons: "As the UK Government, we took our time to assess the facts carefully and independently. We are now confident that Iran was responsible.
"The evidence is clear and there is no plausible alternative explanation."
He added: "This conduct amounts to an armed attack on Saudi Arabia, a violation of one of the basic principles of international law under the United Nations Charter."
Saudi Arabia accused Iran of carrying out the attacks on 14 September, where 18 drones and seven cruise missiles hit an oil field and processing facility.
Mr Raab called for Iran to "come in from the cold" and start abiding by the terms of the nuclear deal.
He added that, as both US President Donald Trump and French President Emmanuel Macron have previously said, "we can improve upon the JCPOA (Joint Comprehensive Plan of Action)".
"Ultimately, we need a longer-term framework that provides greater certainty over Iran's nuclear programme. And, as the attacks on Aramco demonstrate, we must also bring into scope Iran's wider destabilising activities," he said.
That includes, according to Mr Raab, "putting an end to Iran's violations of the freedom of navigation, which are disrupting shipping in the Strait of Hormuz, and undermining the international law of the sea."
The Prime Minister met Iranian President Hassan Rouhani in New York on Tuesday and called for "progress" on the cases of British citizens detained in Iran.
The Foreign Secretary also called for the release of UK-Iranian dual nationals who have been arbitrarily detained in Iran.
"Today there are a range of UK dual-nationals languishing in jail in Iran, typically arrested on spurious charges, denied due process, subject to mistreatment contrary to the basic tenets of international human rights law," Mr Raab said.
"Iran's behaviour is unlawful, it is cruel and it is totally unacceptable."
He added: "I have raised all of these cases, along with Iran's wider conduct with foreign minister Zarif.
"The Prime Minister raised the cases with President Rouhani yesterday in New York and we will continue to press for their release."