Does self-archiving (Green Open Access) violate copyright?

Not as long as you make sure you are depositing and opening the correct version of your manuscript after the embargo period specified by your publisher.

The best way to know which version your publisher allows to deposit and the embargo they require, you can look for the publishing contract you signed when your publication was accepted. Alternatively, SHERPA/RoMEO is an excellent tool to check the standard terms of your publisher. Heloïse is the homologous service for french publishers and journals.