The five-minute video was posted online on Tuesday, just hours after a wave of strikes, including attacks by warplanes and cruise missiles, were launched by the US and partners of a coalition against ISIL targets in Syria.
Reading from a script, Cantlie, who was taken captive by the fighters in 2012 while covering the conflict in Syria, warned that Washington and its allies were embarking on what he described as a "third (Persian) Gulf War", SITE reported.
The footage, which appeared to be made as a form of propaganda by ISIL, showed Cantile saying that "not since Vietnam have we witnessed such a potential mess in the making".
Cantlie says that the strikes against the "most powerful jihadist movement seen in history" could not harm it and quotes statements by US officials warning Washington against battling ISIL.
"Current estimates of 15,000 troops needed to fight ISIL are laughably low. The State has more mujahidin than this," the hostage says. "This is not some undisciplined outfit with a few Kalashnikovs."
The ISIL, which controls large areas of territory in Syria and Iraq, has already executed two US journalists and one British aid worker in recent weeks in what it said was reprisals for US airstrikes against it in Iraq in August.
Cantlie also appears to suggest that US President Barack Obama, long careful to avoid the sort of conflicts his predecessor George Bush pursued, was being sucked into a war he could not win, SITE reported.