Definition under the Merriam-Webster dictionary:
Main Entry: pac·i·fism
Etymology: French pacifisme, from pacifique pacific
1 : opposition to war or violence as a means of settling disputes; specifically : refusal to bear arms on moral or religious grounds
2 : an attitude or policy of nonresistance
I would say under definition #1, aikido does not qualify as "pacifistic."
Under definition #2, I think it actually might qualify.
My own opinion is that aikido does not fall under the category of pacifism. I think it would be hard to label it with a one word description, other than calling it budo. I'm just not able to think of any comparable English word for it. Just my two cents.