1) The days of Chanukah were not set as days of feasting and rejoicing, but as days of thanks and praises, because the [Greek] decrees were not aimed at the body but at the soul. Therefore, the festive meals that are served on Chanukah are not considered mitzvah-meals but ordinary meals. (Shulchan Aruch and Mishnah Berura, section 670)
2) Some say that the extra meals [traditionally served] are somewhat of a mitzvah since it was during these days that the Altar was consecrated in the time of the Chashmonaim, [as was the Mishkan in the Wilderness completed on the 25th of Kislev (the actual erection, however, was postponed until Nissan)]. It is customary to voice songs and praises at these meals; with this additional aspect, the meals are considered mitzvah-meals. (ibid.)
