[mac5732]

sweet talk them for several turns, use the general message option, then send them a gift or two for a couple of turns, Resources or minor Tech that wouldn't hurt you by giving to them, then ask for trade agreement, sometimes they will ask you before you get a chance. Unless your MEE you have a chance to get an agreement and stop the war. Also try not to attack their planets or ships during this time of diplomacy. Some races will respond, others won't. If this doesn't work, then your only choices are glaze their planets and/or mimic them on each other..

just some ideas mac