How can i add ajax button to refresh new content in views pages or block. like new tweets in twitter's timeline.
You can use Views Auto-Refresh module..
Project page says
A module to refresh a view after a specified time interval. Includes advanced options to avoid reloading the whole view, and to avoid causing a full Drupal bootstrap at each refresh.
Suitable for usage on liveblogs, activity streams, comment lists, and any other view where new items are frequently added.