State media said the militants were dressed as local farmers when they hit the position near Taybat al-Imam in Hama around 3 a.m. (midnight GMT). A tank supporting them was destroyed.
“The clash between the guards at the position and the terrorists resulted in three martyrs and the killing of all members of the terrorist group,” state media cited a military source as saying.
There was no immediate claim of responsibility.
The so-called Syrian Observatory for Human Rights said 10 people were killed.
Russia and Turkey struck an agreement last September that staved off a major government offensive into Idlib and adjacent areas of Hama and Aleppo provinces through the creation of the demilitarized zone.
Russian President Vladimir Putin discussed Syria with Turkish President Tayyip Erdogan in Moscow on Monday and they agreed to conduct joint patrols in the area, where Turkey has also deployed forces in militant-held areas.
Idlib and adjoining areas of Hama and Aleppo provinces are largely under the control of terror groups including Tahrir al-Sham, formerly known as the Nusra Front.
Turkish forces control a separate chunk of territory north of Aleppo where Turkey-backed Free Syrian Army rebels are based.