Speaking to FNA here on Monday, Karami blasted the Al-Saud regime for its arrogant attitude towards Iran, and said Tehran has repeatedly warned Saudi Arabia over Syria.
"On the basis of its defensive doctrine, Iran will defend those countries which are in the frontline of confrontation against the US and Israel. Syria is in the frontline of campaign against Israel and Iran, along with the Syrian nation, will not allow the US, Israeli and Saudi plots to be practiced in Syria."
"Iran announces its policies officially and pursues them through action," he said, and added that "the failure of Saudi Arabia and the United States in Syria is for sure."
"The Saudi regime is expected to think of the outcome of its anti-Iranian moves and compliance with the US and is also expected to revise its discourse and literature about Tehran," he cautioned.
Syria has been experiencing unrest since last March with organized attacks by well-armed gangs against Syrian police forces and border guards being reported across the country.
Hundreds of people, including members of the security forces, have been killed, when some protest rallies turned into armed clashes.
The government blames outlaws, saboteurs, and armed terrorist groups for the deaths, stressing that the unrest is being orchestrated from abroad.
In October, calm was eventually restored in the Arab state after President Assad started a reform initiative in the country, but Israel, the US and its Arab allies are seeking hard to bring the country into chaos through any possible means. Tel Aviv, Washington and some Arab capitals have been staging various plots in the hope of stirring unrests in Syria once again.