The agreement was signed by chief of staff of the Iranian Armed forces Mohammad Bakeri and Syrian defense Minister Ali Abdullah Ayyub in the Syrian capital of Damascus.
"As part of the agreement, Iran will strengthen Syria's air defense system. This cooperation between the two countries will increase our ability to resist US pressure, " Bakeri said.
According to him, the countries of the region do not welcome the presence of the United States on its territory.
The Iranian commander also called on Turkey to resolve problems with Syria through dialogue.
For his part, Ayoub said the United States "failed to bring Iran, Syria and the resistance front to their knees."
"Iran has been the main ally of the Syrian government in its fight against armed rebels since 2011," the Syrian defense Minister said.