"We consider the threats from Jerusalem's occupying regime (Israel) as a sign of weakness," Mousavi said in a statement.
Israeli threats are also "desperate attempts to cover up the crises and domestic problems of its leaders," he added.
Highlighting Iran's ability to protect its national security, the spokesman said his country "will give a crushing regretful response to any act of aggression or stupid action."
On Sunday, the Israeli defense minister warned Iran against continued presence in Syria, saying Israel will "work tirelessly" to prevent the establishment of a stable Iranian military presence in the Arab country.
Moreover, Israeli Foreign Minister Yisrael Katz said the Israeli government was considering military action against Iran should it pursue nuclear military capability.
Iran has repeatedly said its presence in Syria is of advisory nature for the government of President Bashar al-Assad, and its nuclear program is civilian.