france
Not copyright infringement
"Fair use" does not exist in France, but something similar is at §3 of article L122-5 of the intellectual property code:
Lorsque l'oeuvre a été divulguée, l'auteur ne peut interdire :
(...)
3° Sous réserve que soient indiqués clairement le nom de l'auteur et la source :
a) Les analyses et courtes citations justifiées par le caractère critique, polémique, pédagogique, scientifique ou d'information de l'oeuvre à laquelle elles sont incorporées (...)
Once a work has been published, its author cannot forbid
(...)
3° Under the condition that the name of the author and the source be clearly indicated:
a) Analyses and short citations justified by an interest of criticism, debate, pedagogy, science or information, of the work within which it is incorporated (...)
Assuming for the sake of argument that the test for paragraph 3(a) is satisfied, there is no copyright violation if the citation requirements of 3° are satisfied.
Probably not defamation
A "courtesy of" mention can be understood as an assertion that the copyright holder gave permission to reproduce the work. That is a factual statement (and a false one, per our hypothesis).
However it is not enough that the statement be false to be defamatory; it has to "impunge on the honor or consideration of the person [or corporation] to which the action is attributed" (see article 29 of the law about press freedom).
In general that would not be true - giving permission to use stuff is widely seen as a nice thing to do. Even if it was defamatory, it usually would be very mild (and hence not worth pursuing legal action against). I can conceive some very specific cases where it would end up in court; for instance, if a prominent neo-Nazi publisher reproduces a quotation "courtesy of rabbi Hertzl" as part of some antisemitic screed, with the implication that rabbi Hertzl supports that publication.
Finally, a note about the practicalities of redress. Putting a monetary amount on non-tangible damage (reputational, emotional, etc.) is always difficult, but the French doctrine is (to a first approximation) "receipts or get out". A very common monetary award is the symbolic amount of €1; a very large portion of successful defamation cases (possibly more than half) end with that award. The more substantial redress in cases of defamation is judicial publication (where a newspaper who published a defamatory article is forced to publish the court’s judgment in the next issue with the same prominence as the original article), which would not be available in the US (where the first amendment prohibits compelled speech).