"We are against Ankara's establishing of military posts in Syria ... The issues should be resolved by diplomatic means ... Syria's integrity should be respected," Mousavi told a weekly news conference, broadcast live on state TV.
On Thursday, Turkey agreed in talks with U.S. Vice President Mike Pence to a five-day pause in an offensive into northeastern Syria, to allow time for the Kurdish fighters to withdraw from a "safe zone" Ankara aims to establish near its border with Syria.
Turkey's President Tayyip Erdogan said on Saturday that Ankara would press on with its offensive into northeastern Syria and "crush the heads of terrorists" if a deal with Washington on the withdrawal of Kurdish fighters from the area was not fully implemented.
A close ally of Syrian President Bashar al-Assad, Iran has offered to engage Syrian Kurds, Syria's government and Turkey in talks to establish security along the Turkish-Syrian border following Turkey's military incursion into northern Syria to fight Kurdish forces.