Speaking in a meeting with visiting Syrian President Bashar al-Assad in Tehran on Saturday, the Leader described the US as the main opponent of the regional axis of resistance.
The Leader said Iran and Syria's political relations are "excellent" and expressed satisfaction with economic and technical cooperation between the two countries.
"There is still much potential to expand such [bilateral] cooperation," Ayatollah Khamenei said.
"There are no two countries in the region which enjoy such strong, excellent and mutual 30-year relations," the Leader added.
Ayatollah Khamenei emphasized the importance of promoting cooperation among neighboring countries in the region and expressed hope Iraqi groups would maintain unity and work towards rebuilding Iraq, resolving the Iraqi nation's problems and ending the occupation of their country.
The Syrian president, for his part, described Tehran-Damascus relations as "exemplary" and stressed, "Iran and Syrian are on the same front and have the same goals."
Assad reiterated that the two countries would expand relations in all fields and achieve greater success in the region.
The Syrian president, who arrived in Tehran on Saturday, wrapped up his one-day visit, following the meeting.
Earlier in the day, Assad discussed the latest regional and international developments with Iranian President Mahmoud Ahmadinejad.
Assad received the Grand National Order of the Islamic Republic of Iran for his resistance against arrogant powers, defense of the rights of the Palestinian and Lebanese nations, his key role in the stability and tranquility of regional countries and great efforts to strengthen brotherly Iran-Syria ties.