Assad says the alternative would have been to leave the civilians in the once contested city to the mercy of "terrorists," a term the government uses to describe all those opposed to its rule.
The remarks, given to French press, were carried by Syrian state media today. Once Syria's largest city and industrial hub, Aleppo has been devastated by nearly six years of war.
Rebels took control of its eastern districts in 2012, before surrendering it to government authority last month.
The UN said the government's relentless military campaign, which displaced tens of thousands of civilians, could have violated the laws of war.