If you want to export the underlying data then you can use
Export --> Data.
This will give you option either to export the summary or underlying data.
But kindly remember that it will not contain any formatting and downloaded as csv file.
Thanks for advise but i am looking for something else. I know about the functionality which you have mentioned in your response but i want a button sort of a thing on a dashboard on server, by clicking on which I can get get the data exported to excel. This data export should be based on filter/parameter selection.
The default download to csv option on Tableau server will not preserve any filters you set on it
One alternative is to use tabcmd:
Specifying the filter: tabcmd export png with parameter filters?
Downloading a csv: tabcmd Commands
The other option is to use the javasccript API and embed a button into your custom portal with your viz (if you have one)
Hope this helps