The decree, expected to be approved on Thursday, puts into effect measures originally drafted in 2012 giving Rome so-called golden powers over key financial infrastructure.
It will force non-European Union players to notify Rome of any takeover intentions or plans to acquire stakes in such assets.
The powers would allow the government to oppose any move by a non-EU player to acquire an interest in the Milan bourse which is controlled by the London Stock Exchange.
Earlier this month the Hong Kong bourse made an unsolicited takeover bid on the LSE which was rebuffed by the UK group.
But HKEX, the Hong Kong Exchanges and Clearing, has refused to give up on its bid, insisting it will now hold more talks with LSE investors.
It was not immediately possible to get a comment from the Italian Prime Minister's office.
(Reporting by Giuseppe Fonte and elvira Pollina, writing by Stephen Jewkes)