Turkey's downing of a Russian fighter jet "sends the wrong message to the terrorists" in Syria, Iranian Foreign Minister Mohammad Javad Zarif told his Russian counterpart Sergei Lavrov late Tuesday.
"Such actions will lead to an escalation of the Syrian crisis and sends the wrong message to the terrorist groups," foreign ministry spokesman Hossein Jaber-Ansari quoted Zarif as saying.
"Any measure that increases tensions and complicates the situation will be a wrong signal to the terrorists," he said.
It makes them "believe they can continue their terrorist activities ... by exploiting the division of views among the parties."
Turkish fighter jets shot down a Russian warplane on the Syrian border on Tuesday, in what President Vladimir Putin described as a "stab in the back committed by accomplices of terrorists".
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Turkey said the Russian plane had violated its air space 10 times within a five minute period, but Russia insisted it had never strayed from Syrian territory.
Iranian President Hassan Rouhani described the downing of the plane as "very alarming and dangerous".
"As far as our information indicate, this plane was targeted when operating in Syrian territory," Iran's official IRNA news agency quoted him as saying on Wednesday.
Turkey is a major backer of rebels who have been fighting loyalists of Syrian President Bashar al-Assad since 2011, although it also joined a US-led coalition fighting the Islamic State group in Syria earlier this year.
Russia and Iran are the main foreign backers of Assad's regime against the rebels.
Moscow launched a bombing campaign in Syria on September 30 but critics, including Ankara, say it has mainly targeted moderate and Islamist rebel groups, rather than IS.