Tehran and Damascus are both under heavy Western sanctions.
Analyst Danura said the regional climate following the Saudi-Iran rapprochement made Raisi’s visit “more appropriate”.
Assad is hoping that a full normalization of relations with the wealthy Gulf monarchies and other Arab states will also help rebuild finances.
In April, Saudi Foreign Minister Prince Faisal bin Farhan made the first visit to Damascus by a Saudi official since the start of the war.
On the ground, Iran-backed groups including Lebanon’s Hezbollah continue to reinforce Assad’s forces, while Iran says it only deploys military advisers to Syria.
Iran’s foreign ministry spokesman Nasser Kanani said this week that “fighting terrorism is one of the successful examples of cooperation between the two countries.”
“We were with the Syrian nation during the difficult years caused by organized attacks by multinational terrorists… and we will be with the Syrian nation during the construction period,” he said.
Damascus considers all who oppose it “terrorists”.
Analyst Danura said he expected Syria-Turkey relations to also be discussed.
Tehran has been part of four-way talks with Damascus, Moscow and Ankara seeking to improve Syrian-Turkish ties, which broke down at the start of the conflict.
