Turkish President Erdoğan holds closed-door meetings in New York
Turkish President Erdoğan (L) and his Iranian counterpart Hassan Rouhani
The closed-door meeting with Guterres came a day before Erdoğan's address to the General Assembly's 73rd session.
The UN said Guterres "commended the excellent UN-Turkish cooperation, including in support of Turkey’s hosting of more than 3.5 million refugees".
"The Secretary-General and the President discussed the situation in Syria, with the Secretary-General welcoming the agreement reached on 17 September to create a demilitarized zone in Idlib," the UN said in the statement.
Later, Turkish presidential sources, who spoke on the condition of anonymity due to restrictions on talking to media, said the two men confirmed their resolution to further develop close cooperation between Turkey and the UN.
Erdoğan and Guterres also discussed measures taken for the de-escalation zone in Idlib following a deal between Ankara and Moscow in the Russian city of Sochi as well as the political process in Syria.
Some key global and regional issues were also addressed, according to the sources.
Turkey and Russia also signed a memorandum of understanding on that date calling for the "stabilization" of Idlib's de-escalation zone, in which acts of aggression are expressly prohibited.
Under the pact, opposition groups in Idlib will remain in areas where they are already present while Russia and Turkey will carry out joint patrols in the area to head off renewed fighting.
On Sept. 24, Erdoğan also held closed-door meetings with Japanese Prime Minister Shinzo Abe and Iranian President Hassan Rouhani in New York.
The theme of this year's general assembly meetings is Making the United Nations Relevant to All People: Global Leadership and Shared Responsibilities for Peaceful, Equitable and Sustainable Societies.
Erdoğan's schedule in New York runs through Sept. 26.
Turkish Foreign Minister Mevlüt Çavuşoğlu, Defense Minister Hulusi Akar, Health Minister Fahrettin Koca and Industry and Technology Minister Mustafa Varank were also present at the meeting.