I think for transfer of tablespace's from one endian format to another endian format you must use RMAN Convert command either on the source or target systems. Query v$transportable_platform to get the target platform name.

Bring the tablespace to read only mode

on the source platform
Example:
rman>convert tablespace 'SAMPLE'
to platform='AIX Based(64 bit)'
db_file_name_convert='/u01/oradata/index01.dbf','/usr/tmp';

copy the file to target and import the metadata and bring the tablespace online.