No, wars must be obligatory. You are of course free to not win them... and since they can make it so that you do not lose no resources when you are attacked, what does it matter?
You can search for alliances by name and then declare war on them, or declare war on any alliance showing in either the current competition leaderboard or in the persistent leaderboard. You will soon know the names of many alliances that you will wish to declare on. It is not a problem at all. It just needs to get started to get the ball rolling...