Khamenei met Monday in Tehran with Omani Sultan Qaboos bin Said al-Said to discuss regional affairs.
"The main reason for the current situation of the region is ... interference from outside the region," the cleric was quoted as saying by Iran's state-funded broadcaster Press TV.
Iran has sided with Syrian President Bashar Assad on the best way forward in embattled Syria.
In Egypt, hundreds of people have died in the weeks that followed a July 3 military decision to unseat the democratically elected government of Mohamed Morsi.
Western powers expressed support for democratic ambitions in Egypt, Tunisia and Libya.
Post-revolutionary governments in those countries have struggled to endure.
Khamenei said foreign powers "must know that they will not be immune to the fire they started" in the region.