Not directly; Oracle's IMPORT utility (or Import Data Pump in latest version) can read only files made by Oracle's Export utility.
However, there are several possibilities: export data from DB2 table into the CSV file and load it into Oracle using SQL*Loader or use it as an External table. Furthermore, you could use Oracle Migration Workbench, a tool that simplifies the process of migrating third-party database systems to the Oracle platform (Oracle9i and Oracle10g). The Oracle Migration Workbench migrates the entire database schema, including triggers and stored procedures, in an integrated, environment.
Oracle tool is only doing almost the same you suggested me: export from db2 in a flat file, then import in oracle. The real problem is that I have clob datas in one column so, as far as I read in release notes of oracle migration tool, this datas can't be exported in flat files. So, I'm lost ... ?