Larijani made the remarks at a joint press conference with his Syrian counterpart Muhammad Jihad al-Laham.
The top Iranian parliamentarian also lauded the resistance of the Syrian nation against terrorism, saying that Syrian people have managed, to a great extent, to foil the plots hatched by the "adventurous” terrorists through steadfastness.
Syria has been beset by a deadly crisis since March 2011. The ongoing militancy has reportedly claimed the lives of over 222,000 people. Many western countries and their regional allies especially Saudi Arabia, Qatar and Turkey are among supporters of the militants fighting the Syrian government.
Larijani further criticized certain countries in the world and the region for supporting terrorist groups in Syria and Iraq.
He warned against the spread of terrorism and called on the regional countries to uproot the scourge.
The Iranian speaker further expressed hope that "the Syrian nation will emerge victorious” in the battle against terrorists.
Al-Laham, for his part, praised the Islamic Republic’s backing for the Syrian nation and government in the face of militancy in the country.
"Our region is threatened by terrorism, which is backed by the colonial powers and some of our neighbors," al-Laham said. "We are in Tehran to further coordinate our cooperation."
Heading a parliamentary delegation, al-Laham arrived in Tehran on Monday to hold talks with senior Iranian officials.
He said cooperation between Tehran and Damascus has been a factor of stability in the region, adding it will serve as a barrier against threats to the security of the region.
Al-Laham also criticized some Western countries for exerting sanction pressures against Syria, which has impacted the lives of the Syrian people.
Iran has vowed "unlimited" support for Syria in its fight against foreign-backed militants.