President Hassan Rouhani said Iran would make or buy any weapons it needed to defend itself in a region beset by "invading powers", as the military paraded missiles and soldiers in front of him on National Army Day.
Fighter jets and bombers flew overhead as Rouhani told the Tehran crowd and a live TV audience on Wednesday that Iran's forces posed no threat to its neighbors.
"We tell the world that we will produce or acquire any weapons we need, and will not wait for their approval ... We tell our neighboring countries that our weapons are not against you, it's for deterrence," Rouhani said.
"We are not living in a normal region, and we see invading powers have built bases around us. Disregarding the principles of international law, they intervene in regional affairs and invade other countries without UN permission," Rouhani added.
US, British and French forces pounded Iran's ally Syria with air strikes early on Saturday in retaliation for a suspected April 7 chemical weapons attack, which they blame on Syrian President Bashar al-Assad's government.
Britain, France and Germany have proposed fresh EU sanctions on Iran over its ballistic missiles and its role in Syria’s war, in a bid to persuade US President Donald Trump to preserve the 2015 nuclear deal with Tehran.
Trump has delivered an ultimatum to the European signatories to fix what he saw as the "terrible flaws" of the deal, threatening to refuse to extend US sanctions relief on Iran.
US sanctions will resume unless Trump issues fresh waivers to suspend them on May 12.