Allocate specific tablespace

 I have a user called "X" with tablespace "tablesp_X" , and another 

user called "Y" with tablespace "tablesp_Y", the user "X" contains a lot of tables in 

it's schema but the user Y is empty.

I want to copy the data of the X and import it to Y

so I made export from the user X and created a dmp file then I went to Y and made import using the following command :

Imp Y/Y@conn_string file=\path\mydmpfile.dmp log=\path\logfile.log 

the import operation run successfully but the problem that :

when I checked the objects of Y, I found them allocated in the tablespace