Does 'deed of love' mean deed caused by love or it mean something else?
Life and hope for the world are to be found only in the deeds of love.
In this context, yes, it means deeds that are motivated by love, or that show love.
Careful, though. It could have a much more physical connotation in some contexts. The more usual term for that, being poetic in this way, would be acts of love, but I've come across deeds used for the same thing.