Yes, you must cite any image you use. Yes, that includes Creative Commons.
Manet, Edoaurd. The Dead Toreador. 1864, National Gallery of Art, Washington, DC, http://www.nga.gov/content/ngaweb/Collection/art-object-page.1179.html.
Most databases offer images. Cite image as a short work from a website.
Creative Commons is a source for images. The images included in Creative Commons have a modified copyright which means the copyright owners have voluntarily relinquished some of their rights as a copyright owner.
These copyright modifications are significant for people who need images for commercial use. When you see "no attribution required" that is for when an image is used for commercial purposes. The copyright owner is telling people that you can use the image without having to contact him first to ask permission, and that you do not have to give him credit for the image.
PLEASE BE AWARE: The rules of good scholarship always apply when using someone else's work for academic purposes.
If you have a blog, website, or business you may use a "no attribution required" image freely.
If you are doing a project for school, you must cite it.
Example: Online photograph-
Hura, Sohrab. Two Brothers Toil. 2015, Magnum Photos,
Example: Artwork from a museum website
Manet, Edoaurd. The Dead Toreador. 1864, National Gallery of Art, Washington, DC,
Example: Image from a website
Should be cited as a short work from a website
Artist (if provided) last/first. "Title." Title of Website, update date (if provided), URL. Accessed date ONLY IF NO UPDATE/COPYRIGHT DATE PROVIDED
Example: Image found in a book
Artist last name, first. Work of Art. Year produced (if known). Book information:Title of Book, by author, publishing company, copyright date, p.number.
Kertesz, Andre. Meudon. 1928. Street Photography: From Atg e to Cartier-Bresson, by Clive Scott, Tauris, 2011, p. 61.
*If you see it in person, follow the guidelines provided by Oregon School for Artwork, Image, Object, Artifact
From A Writer's Reference, 8th Edition updated 2/7/17