Thank you for your question. I am sorry for the delay in answering, which is due to the fact that I am one of the few EU law experts here, and I do have a main job.
To answer your question, the equivalent of "notarization" in French law is "attestation de signature" and this can only be done, in France, by a Notary Public, not a lawyer. You can find an English list of notaries in Paris here: http://notaries-europe.com/france/paris/
Note that once they do the formality, you need to apply the Apostille on the document, something that they can help with.
Alternatively, and without needing to go through any other formality, you can use the services of the US Embassy - Consular Section. Details here (https://fr.usembassy.gov/u-s-citizen-services/notarial-services-all-nationalities/documents-we-notarize/).
I hope my answer was useful and look forward to your rating, which is essential to my activity.
Dr I L Vlad