Iran's President warned on Wednesday that fighting between Azeri and ethnic Armenian forces in the South Caucasus could spark a regional war and stepped up calls for a ceasefire.
"We must be attentive that the war between Armenia and Azerbaijan does not become a regional war," President Hassan Rouhani said in televised remarks.
Rouhani also warned Iran will not tolerate "terrorists" near its border with Azerbaijan, after France and Russia raised the alarm over the deployment of Syrian militants in the Karabakh conflict.
"It is unacceptable for us that some people want to send terrorists from Syria and other places towards regions near our frontiers," Rouhani said.
Iran borders Armenian-held areas of Azerbaijan near Nagorno-Karabakh that have seen fighting.
Turkey has been accused of deploying fighters from Syria to support Azerbaijan in Karabakh.
French President Emmanuel Macron said Ankara had sent Syrian militants to the region, accusing Turkey of crossing a "red line".
Russia and Armenia have also said that fighters from Syria and Libya are being deployed on the Azeri side in the conflict.
Rouhani, which has good relations with both Yerevan and Baku, reiterated Wednesday that "occupation is in no case acceptable".
"Everyone" must "accept the reality... and respect other countries' territorial integrity", he said.
Rouhani at the same time condemned "those who, on one side or the other, pour oil on the fire", without naming Turkey which has declared open support for Azeri military action to reclaim the enclave.
Iran has called on both Armenia and Azerbaijan to cease hostilities and offered to facilitate talks.
On Saturday, Tehran warned against any "intrusion" after mortar fire hit Iranian villages along the border.
