"Wait for surprises regarding the fate of the captured troops," Al-Nusra wrote via Twitter.
Together with its message, the group published photos of some of the troops showing them bound and lying on the ground as five militants pointed guns at them.
Al-Nusra, one of several militant organizations fighting the Syrian regime, has captured 17 Lebanese troops.
ISIL meanwhile, another militant group that has captured vast territories in both Iraq and Syria, has captured six Lebanese troops.
The two groups captured the soldiers last August following clashes with the Lebanese army in the Lebanese town of Arsal on the Syrian border.
ISIL and Al-Nusra have each executed two of the Lebanese troops that they captured.
On Monday, Lebanese security forces raided a cell in Roumieh Prison in which Islamists had been held. Several people from both sides were injured in the ensuing clashes.
Since the Lebanese army clashed with Al-Nusra and ISIL last August, Lebanon has become increasingly caught up in the Syrian quagmire.