Iran's Supreme Leader Ayatollah Ali Khamenei accused the U.S. of using the "pretext" of chemical weapons to attack Syria, and warned on Thursday that America will "suffer" if it decides to intervene in the conflict.
"The United States is wrong about Syria, and it is certain they will suffer... just like in Iraq and Afghanistan," Khamenei said, according to Al Jazeera.
The chief of Iran's elite Quds Force unit, Qassem Soleimani, added in a separate statement that Iran would stand behind Syria "until the end."
"The aim of the United States is not to protect human rights ... but to destroy the front of resistance (against Israel)," Soleimani was quoted in a speech.
Iran is warning Western powers against attacking the government of President Bashar al-Assad, who the Obama administration says is behind the chemical attacks in August that killed 1,429 people, including more than 400 children.
President Barack Obama is hoping to win final Congressional approval on a limited strike on Syria, which he says is needed to stop Assad's regime from continuing attacks on civilians. The two-year long civil war in Syria between government and rebel forces has already claimed more than 100,000 lives, with no clear end in sight.
While Obama has insisted that America's goal in Syria is to protect civilians who are paying a high price in the war, some critics have accused the U.S. of trying to impose its will on the region and blunt Iran's influence in the Middle East, which it fears poses a threat to Israel.
Russian President Vladimir Putin has also warned the U.S. that any attacks on Syria not authorized by the U.N. would count as "aggression," though he did not say what, if any, actions Russia was prepared to take in such an event.
"Any action against Syria is against the interests of the region but also against the friends of the United States in this region," added Iranian President Hassan Rouhani. "Such action will help nobody."
Despite a lack of support from the U.N. and key allies such as the U.K., the U.S. Senate Foreign Relations' Committee voted on Wednesday 10-7 in favor of limited strikes on Syria, although the plan must also go through a wider Senate vote and then a House vote before Obama is given Congressional approval.
The U.S. president warned of the consequences of not acting in Syria in a statement over the weekend:
"This attack is an assault on human dignity. It also presents a serious danger to our national security. It risks making a mockery of the global prohibition on the use of chemical weapons. It endangers our friends and our partners along Syria's borders, including Israel, Jordan, Turkey, Lebanon and Iraq," he said, arguing for military intervention. "It could lead to escalating use of chemical weapons, or their proliferation to terrorist groups who would do our people harm."
Obama added: "In a world with many dangers, this menace must be confronted."