Iran's deputy foreign minister says the situation in its ally Syria is "very complicated" amid growing concern a wider regional war could erupt, reports BBC.
"Fear of war is everywhere in our region," Abbas Araqchi told the BBC.
It comes after Israel targeted Iranian sites in Syria earlier this month.
Mr Araqchi told the BBC's chief international correspondent Lyse Doucet in London that Iran's presence in Syria was not aimed at creating a new front against Israel, but to fight terrorism.
"Just imagine if we were not there. Now you would have Daesh [the Islamic State group] in Damascus, and maybe in Beirut and other places," the minister said.
He deplored the suffering in the Damascus suburb of Ghouta where Syrian bombing in the past few days has killed scores of civilians.
War of drones
Mr Araqchi added that Iran-backed militia such as Lebanon's Hezbollah - which has also fought in Syria on the side of the Syrian government - existed to confront Israel. Mr Araqchi also refused to confirm that Iran had sent a drone into Israeli airspace from Syria earlier this month. He said the drone belonged to the Syrian army.
An Israeli warplane targeting Iranian sites in retaliation was shot down by Syrian air defences.
This week Israeli Prime Minister Benjamin Netanyahu brandished what he said was part of the drone at a security conference in Munich and said Iran was the "greatest threat to our world".
But Mr Araqchi said Israel was flying drones over Syria and other neighbouring countries.
"They shouldn't be angry when they are faced with something that they are doing against others on a daily basis," he said.
Nuclear deal at 'critical' moment
Mr Araqchi also said that the 2015 Iran nuclear deal was at a "critical moment" following US threats that sanctions on Iran could be re-imposed. Last month President Donald Trump said the deal's "terrible flaws" had to be fixed.
Iran's deputy foreign minister said he did not believe the deal could survive without the US.
The landmark accord between six global powers and Iran obliges Iran to agree to reduce uranium enrichment activity, dispose of enriched uranium stocks and modify a heavy water facility in return for sanctions to be lifted.
However the White House wants EU signatories to agree permanent restrictions on Iran's uranium enrichment. Under the current deal they are set to expire in 2025. Mr Trump also wants Iran's ballistic missile programme to be addressed.
But Mr Araqchi said the US had to fulfil its side of the deal, formally known as the Joint Comprehensive Plan of Action (JCPOA) before other issues could be discussed.