Is it necessary to have image creative common license for reuse in my website. or I can use any images appeared in image search for my website.
You need to be sure you have permission to post the images. A creative commons license that allows reuse for commercial purposes would be appropriate for a site with AdSense ads.
Search Results - Unless they are under CC license, you need a permission CC License - You need not take permission but you need to link back to the source of the image
Not necessarily true. There are different CC licenses - some allow you to use an image with just a link back, others have limitations. For example some say you cannot use the images for commercial purposes (which a web site with ads or that sells things would likely be considered).
My photo dictionary has around 2000 CC commercial use images (at the time of sourcing - I did have one person immediately complained I used his image, changed it to all rights reserved and demanded a takedown from my ISP, which I thought was rude. Why license CC for commercial use if you won't let anyone use it? Most people are happy their image was used), maybe two or three from the public domain that had info on the source site that you could use them, and another handful from Google image search. The latter I asked the owners if I could use them. Copyright infringement is a hassle.