U.S. President Barack Obama, during an address Tuesday to the U.N. General Assembly, said there was no room for Syrian President Bashar Assad in the future of the country.
"The future must not belong to a dictator who massacres his people," he said.
The U.N. Security Council has been unable to reach a consensus on Syria because of concerns by Russia and China that resolutions lacked balance.
Iranian Foreign Minister Ali Akbar Salehi told U.N.-Arab League envoy to Syria Lakhdar Brahimi that foreign interference wasn't resolving the ongoing situation in the country.
Salehi told the Algerian diplomat that "Tehran believes that the Syrian crisis would be settled through coordination among all belligerent sides," the official Islamic Republic News Agency reports.
Brahimi told the U.N. Security Council the situation in Syria was "very grim." U.N. humanitarian officials and international human rights groups suspect both parties to the conflict are committing war crimes.
Nevertheless, Brahimi struck a positive note following recent meetings with the Syrian president.
"Now that I have found out a little more about what is happening in the country and the region, I think that we will find an opening in the not-too-distant future," he said in a statement.
The United Nations estimates more than 18,000 people, mostly civilians, have died as a result of the conflict that began in March 2011.