I'm making some assumptions that might mean this answer doesn't apply the specific situation you have in mind.
Don't trust Google's labelling
Google can index images by license type, such as "labeled for reuse", or "labeled for reuse with modification", etc. However, I notice this indexing isn't perfect. Some of the images indexed under "labeled for reuse" are public domain images. I would have expected these to be indexed under "labeled for reuse with modification". There are two takeaways from this: Google's shorthand isn't a licence, and Google's indexing isn't perfect. You have to look to the original source to determine what license the content is available under. An alternative search engine that better indexes based on license is Creative Commons Search.
What does no derivatives mean?
Let's assume you find an image licensed as Creative Commons Attribution-NoDerivatives (CC BY-ND). What does the "no derivatives part mean?"
The license summary says:
If you remix, transform, or build upon the material, you may not distribute the modified material.
More specific language is in the actual license.
Adapted Material means material subject to Copyright and Similar Rights that is derived from or based upon the Licensed Material and in which the Licensed Material is translated, altered, arranged, transformed, or otherwise modified in a manner requiring permission under the Copyright and Similar Rights held by the Licensor.
A crop is an alteration. The Creative Commons FAQ says, "You must also indicate if you have modified the work — for example, if you have taken an excerpt, or cropped a photo".
You may "produce and reproduce, but not Share" this "Adapted Material".