。
I don't think we should make exceptions.
Literal
Exceptions [topic-は] should-not-make [quotative-と] think [polite-ます].
~べきではない ('should not X') is the negative of ~べき (obligation 'should, ought to'). より formal than ~ない方がいい. Combined with と思います, it's a polite opinion ('I think we shouldn't'). Standard formal debate register.