Google Adsense Policies strictly prohibit Adsense users from including incentives of any kind for users to click on Google ads. For example, your site cannot contain phrases such as "click here," "support us," "visit these links," or other similar language that could apply to any ad, regardless of content.Here's a different kind of issue that's probably an Adwords violation.
Today, I found atleast two Google 300x250 image banners on my website that highlighted the term "Click Here." The banner on the top is from Mommy Care that sells stretch mark creams for pregnant women. The second banner of sparklepeople shows an animated GIF that highlights CLICK HERE and also blinks near the text.
Just curious to know Google's response on this ad. Probably they approved the ad but missed the "Click here" text.