In a phone conversation on Tuesday, the two sides pointed to political solution as the only way out of the crisis in Syria.
Amir Abdollahian reaffirmed Iran’s continued support for the nation and government of Syria in their fight against terrorism.
De Mistura, for his part, referred his recent talks in Geneva, Switzerland, with Syrian parties and described them as "positive and constructive".
The UN envoy is scheduled to pay an official visit to Tehran, capital of Iran, as part of his regional tour aimed at further consultations.
Syria has been gripped by civil war since March 2011 with Takfiri (extremist) terrorists from the ISIL (Islamic State in Iraq and the Levant) currently controlling parts of it, mostly in the east.
In the past four years, more than 200,000 people have died in Syria - overwhelmingly civilians - and around 4 million Syrian people are now refugees in other countries. Another 7.6 million are displaced inside Syria.
The terrorist group claims as an independent state the territory of Iraq and Syria, with implied future claims intended over more of the Levant, including Lebanon, occupied Palestine, Jordan, Cyprus, and Southern Turkey.