Iranian Foreign Minister Mohammad Javad Zarif traveled to Damascus on Monday for talks with Syrian officials, the Tasnim news agency reported.
Iranian forces have backed Syrian President Bashar al-Assad in the country’s civil war.
Last week, Iran's defence minister traveled to Damascus and signed an agreement for defence cooperation between the two countries with his Syrian counterpart.
Iranian President Hassan Rouhani is scheduled to meet Russian President Vladimir Putin and Turkish President Tayyip Erdogan in Iran, Iran's foreign ministry spokesman Bahram Qassemi said Monday, according to Fars News.
"I'm optimistic that this meeting will be successful and productive for the region, the people of Syria and the fight against terrorism," Qassemi said.
Fars News said the leaders would meet on Friday.
The meeting comes as Syrian government forces are preparing a phased offensive in the northwestern province of Idlib and surrounding areas, the last big rebel enclave.
"One of the complicated issues today is Idlib which is the last stronghold of anti-government insurgents. The government of Syria is determined to put an end to this catastrophe, Qassemi said, according to Fars News.
"The government of Syria has the right to fight against terrorists in this region. And Iran, as a supporter of the Syrian government, is present and will continue its advisory help as long as the Syrian government wants."