Are you using Delevent?
What HT said.
The only other way I can think of (but haven't tried) is to use the attitude modifier event in ToT. You just make x civ love you every turn. Thing is, Civ2's AI has a tendency to completely change its attitude towards you in a turn--it won't necessarily declare war until later though.
Then you can try working with the AI--I heard some hysterical screaming, was that you? Actually, there are ways of making the AI 'like' you but it's rather like a first date, there's a lot of balancing involved.
Give the AI the same techs as you so that it won't want anything from you--i.e. have cause for making war. I'm actually working on BKA's AWAW and can't seem to get the Minor Allies declaring war on the Minor Axis in the first turn without resorting to the NoNeg event.
There are probably a million reasons why the AI acts the way it does during diplomacy, but I don't know the half of them (MGE's AI is also more aggressive BTW).
If the source code were to be released, we could tweak the AI to make it more 'reasonable' but until then, there's not a lot you can do.