How to get url of selected image in google images?
Okay, my way is to ask Safari do javascript which will get all what I need (I mean urls of full-images) for current page, when user presses hotkey.

The trick is that when you select (hower) image, you see a black box at bottom of mini-image. Certanly, it means that HTML has been changed, so I just figured out that changes (display property changes from none to block) and ask JS to get any blocks with that property, when user presses key. 

See code below for details.

tell application "Safari"
set result to (do JavaScript " 
               function f() 
               { 
                   var imageHolderElements =  document.getElementsByClassName('_aOd rg_ilm'); 
                   for (var i = 0; i &lt; imageHolderElements.length; i++) 
                   { 
                       var style = getComputedStyle(imageHolderElements[i], null); 
                       var display = style.getPropertyValue('display'); 
                       if (display == 'block') 
                       { 
                           var src = imageHolderElements[i].parentNode.getAttribute('href'); 
                           var parameter = 'imgurl='; 
                           var index = src.indexOf(parameter) + parameter.length; 
                           console.log(index); 
                           var result = src.substring(index, src.length); 
                           console.log(result); 
                           var paramDelim = result.indexOf('&amp;'); 
                           if (paramDelim &gt; 0){ 
                                var result_result = ''; 
                               result_result = result.substring(0, paramDelim); 
                           } 
                           console.log(result_result); 
                           return result_result; 
                       } 
                   }
               } 
                var x = 1; 
               var x = '' + f(); x" in current tab of first window) as string
return result
end tell