"The military path points directly towards the further disintegration of the country, destabilization of the region and inflammation of religious and communal tensions," Ban told reporters yesterday.
He added that "the flow of arms to either side would not be helpful" as he called for renewed efforts to convene an international peace conference to resolve the two-year-old conflict, which has claimed over 93,000 lives.
The statement came after the United States said it would provide more "direct support" including "military support" to opponents of President Bashar al-Assad.
The United States sent a letter to the United Nations yesterday setting out its evidence on the use of chemical weapons, Ban and US ambassador Susan Rice announced.
The United Nations, United States and Russia are "still working very hard" on efforts to hold a Syrian peace conference in Geneva, Ban said.
But with the conflict worsening, the Syrian opposition divided and international powers split between the two sides, diplomats said the chances of holding a conference are becoming slimmer.