The incident took place in during the Europa League first round match on June 29. Play had to be stopped in order to remove the balls of paper from the pitch.
A statement said: "Rangers FC have been fined €7,000. The charges against Rangers FC were related to the throwing of objects Art. 16 (2) of the UEFA Disciplinary Regulations (DR)."
Rangers went on to win the match 1-0 in Glasgow but were beaten 2-0 in the return leg in Luxembourg, therefore losing 2-1 on aggregate.