Instead of moving all the objects to different tablespace, one temporary approach to solve this is run this sql script which will give the location of segments at the datafile level. Pick up the last object in this result and rebuild in the same tablespace, so that the space unused from the starting of datafile will be now reused. For permamnet solution transfer the data dictionary tablespace to an LMT.

you should give tablespace name as input for this query.

select file_id, block_id, blocks,
owner||'.'||segment_name "Name"
from sys.dba_extents
where tablespace_name =
UNION
select file_id, block_id, blocks,
'Free'
from sys.dba_free_space
where tablespace_name =
order by 1,2,3