The United Nations estimates that about 9.3 million people in Syria need humanitarian assistance due to the country's two and a half years of civil war.
The US and Russia failed on Tuesday to agree a date for a Syrian peace conference, remaining divided over what role Iran might play in talks to end the civil war and over who would represent Syria's opposition.
The policy of pressure ahead of the nuclear negotiations should be abandoned, Iranian Foreign Ministry spokeswoman Marzieh Afkham said Tuesday.
Delegates from the United Nations, Russia and the United States arrived here Tuesday for a trilateral meeting to prepare for the long-delayed peace talks on Syria.
Iranian President Hassan Rouhani said Monday that nobody should expect sanction relief will take place in a short time.
The United States remains committed to holding a peace conference on Syria in Geneva in November as a negotiated solution is the only way to lead Syria out of its current crisis, the White House said on Monday.
An Egyptian court decided on Monday to postpone the trial of Egypt's deposed President Mohamed Morsi to Jan 8, 2014 over the charges of murdering protesters during his one-year rule.
Iran's President Hassan Rouhani said the Islamic republic is "not optimistic" about the results of its ongoing nuclear talks with the world powers.
Trial of Egypt's deposed Islamist president Mohamed Morsi has been adjourned to January 8, 2014, the presiding judge said on Monday.
Tens of thousands of Iranians held demonstrations on Monday across the country to mark the 34th anniversary of the seizure of the US embassy in Tehran.
US Secretary of State John Kerry made a brief tour to Egypt on Sunday, one day ahead of ousted President Mohamed Morsi's trial.
Egypt's ousted President Mohammed Morsi arrived at a Cairo police academy where his trial for incitement of violence and murder will begin shortly.