It is the latest move to stamp out abuses at the Vatican bank, which handles funds for the Catholic Church.
The Pope recently set up a commission to investigate the bank and report back to him personally.
Last month the Vatican froze the account of a senior cleric, Monsignor Nunzio Scarano, suspected of involvement in money-laundering.
He and two others were arrested by Italian police in June on suspicion of trying to move 20m euros ($26m; £17m) illegally.
Pope Francis’s number one priority this summer is to sort out the financial mess at the Vatican bank and a parent body which looks after the financial assets of the Holy See, the BBC’s David Willey reports from Rome.