CKeditor adds extra  tags
You need to set ckeditor configuration setting

config.enterMode


to proper value

(1) The default creates a paragraph element each time the "enter" key is pressed:

config.enterMode = CKEDITOR.ENTER_P; // inserts &lt;p&gt;&lt;/p&gt;


(2) You can choose to create a "div" element instead of a paragraph:

config.enterMode = CKEDITOR.ENTER_DIV; // inserts &lt;div&gt;&lt;/div&gt;



The setting that you are looking for *


(3) If you prefer to not wrap the text in anything, you can choose to insert a line break tag:

config.enterMode = CKEDITOR.ENTER_BR; // inserts &lt;br /&gt;


The application developer indicates that using the ENTER_BR setting is not recommended.
http://docs.cksource.com/ckeditor_api/symbols/CKEDITOR.config.html#.enterMode

There are three more settings that are somewhat related to this subject:

config.fillEmptyBlocks
config.forceEnterMode
config.ignoreEmptyParagraph


A complete list of the available configuration options can be found here:
http://docs.cksource.com/ckeditor_api/symbols/CKEDITOR.config.html