This poem is part of a famous novel Tristan by the medieval German poet Gottfried von Straßburg. You are right that it is German, or Middle High German to be precise (around 1200 A.D.). Tristan is an important work of German literature, but I would advise you to never read it in its original form because Middle High German is not spoken or used anymore, and even native speakers of Modern German will face difficulties understanding it.
On the German MediaeWiki website, I found a very strict translation into Modern German:
Liebe ist so erfüllend,
ein so beseligendes Bemühen
dass niemand ohne ihre Anleitung
zu innerem Wert oder Prestige kommen kann
wie viel edle Lebensführung die Liebe auch bewirkt
wie viel an innerem Wert durch sie auch kommt
ach dass alles, was lebt
nicht nach der Liebe strebt
Because this is still very hard to understand I'll try to render it as close as possible in English.
Love is so fullfilling,
such a fullfilling struggle
that no one without its guidance
can come to inner value or reputation
No matter how much noble lifestyle is caused by love
or how much of inner value you gain from it
alas, everything that lives
does not strive for love
"Inner values" = don't judge a book by its cover. I'm sure there is a better word for it.
So this poem says that love is the only way for someone to get inner values (to get a noble heart). Everything that lives should aspire to love, but it doesn't.