"Ceasefire in essence is definitely a desirable affair," Foreign Ministry spokesman Abbas Araqchi told reporters at his weekly press conference in Tehran on Tuesday as he acknowledged the Syrian opposition group's call.

United Nations chief Ban Ki-moon last week too called on all parties in Syria "to stop fighting and offer this month of peace as a collective present to their people."

Ramadan, which started on Wednesday in Syria, is observed by Muslims around the world with the faithful fasting from dawn to dusk.

Araqchi said the armed Syrian opposition must come to term with holding "national dialogue" with Damascus and putting down arms.

"We advise them to implement a complete truce, put away their weapons and engage in negotiations with the Syrian government," Araqchi said, reiterating Iran's position that militancy offers no solution to the Syrian crisis.

"The only way is national dialogue between the government and all real opposition (groups)," he said.

The conflict in Syria started in March 2011, when pro-reform protests turned into a massive insurgency following the intervention of Western and regional states.

The unrest, which took in terrorist groups from across Europe, the Middle East and North Africa, has transpired as one of the bloodiest conflicts in recent history.

As the foreign-backed insurgency in Syria continues without an end in sight, the US government has boosted its political and military support to Takfiri extremists.

Washington has remained indifferent about warnings by Russia and other world powers about the consequences of arming militant groups.

BA/BA