I have successfully installed PHP intl extension, I have noticed that I should enable the intl extension in php.ini file by removing semicolon and when I did that warning appears told me that the extension already loaded so I have edit the php.ini again and re-add the semicolon for "extension=intl.so" to be like this ";extension=intl.so" how ever the same error from CakePHP still appear, I don't know if the extension is really loaded or not.

Note: I'm using Mac OS X version 10.12.4 PHP Version 5.6.30