"If one wants to address properly the space which Daesh [ISIL] has filled in, one of the clear formulas is to try to address in a peaceful way the political process in Syria… If Syrian conflict would end tomorrow, it would by far easier to address the issue of Daesh," de Mistura said.
The UN special envoy stressed that Islamic State militants are taking advantage of the current "weak environment" and conflict in Syria.
De Mistura added that even though it is up to the Syrian people to find the ultimate solution to the conflict, efforts by international mediators, including Russia, facilitate communication between the country's government and the opposition and need to be continued.
De Mistura called for the sides to the Syrian conflict to cease fire and continue with the political dialogue.
Syria has been engulfed in a bloody internal conflict since March 2011 with government forces fighting various insurgent groups, including Islamic State extremists. According to the Syrian Observatory for Human Rights, the last four years of civil war have claimed more than 210,000 lives.
Between January 26 to 29, Moscow held the first Syrian peace talks since a UN-backed conference in Geneva last year failed to yield any significant results.
Earlier this week, a source in the delegation of Syrian opposition groups told RIA Novosti that a second round of Moscow talks on Syria will take place in late April.
