“The Iranian initiative is not serious and lacks political credibility,” the so-called Syrian National Coalition (SNC) said in a statement on Saturday.
The SNC said the mediation offer was an attempt “to prolong the crisis and increase the complexity”.
In an op-ed in The Washington Post on Thursday, Rouhani tabled the proposal to broker talks between the Syrian government and opposition.
“…I announce my government’s readiness to help facilitate dialog between the Syrian government and the opposition,” read the Iranian president’s op-ed piece.
Rouhani further called for collective efforts to pave the way for national dialogue in regional countries.
“We must join hands to constructively work toward national dialogue, whether in Syria or Bahrain. We must create an atmosphere where peoples of the region can decide their own fates.”
Earlier, German Chancellor Angela Merkel welcomed Rouhani’s proposal, demanding that it be translated into action.
Syria has been gripped by deadly unrest since March 2011.
A very large number of the militants operating inside Syria are reportedly foreign nationals. According to reports, the Western powers and their regional allies, especially Qatar, Saudi Arabia, and Turkey, are supporting the militants operating inside Syria.
In a recent statement, the United Nations High Commissioner for Refugees said the number of Syrian refugees, who have fled the country’s 29-month-long conflict, reached two million.
The UN refugee agency further said some 4.2 million people have also been displaced inside Syria since the beginning of the conflict in the Arab country.