In my opinion, Aikido is a tool, not in itself violent, but capable of being used for violence. Given the circumstances, one can use Aikido in a non-violent way, i.e. to tenkan past an attacker and out of his range, or in a violent way, i.e. using kaitenage to drop him forcefully on his head - a potentially fatal technique.
So, Aikido in itself is not violent, but one can use it for violence if one chooses.