The action is the latest move in Pope Francis' drive to clean up the finances of the Holy See, its chief magistrate said.
Gian Pietro Milano, the tiny state's Promoter of Justice, said it brings the total amount frozen between 2013 and 2016 to €13m (£11.1m).
The latest asset freeze followed alerts from the Vatican Financial Intelligence Authority (AIF), which has been given more power by the Pope.
No further details of what lay behind the actions were released, but Mr Milano said that two cases led to indictments and three were shelved.
Moneyval, the Council of Europe's financial monitoring body, said in December 2015 that the Vatican had made great strides in cleaning up its scandal-plagued banking system and other finance departments.
In late 2015, an investigation was opened into property investments that were linked to possible money laundering, insider trading and market manipulation.
In 2014, millions of euros were frozen in bank accounts owned by two former Vatican bank managers and a lawyer.
None of those cases have so far led to indictments.
Mr Milano said the Vatican had "closed the gap" on meeting international standards regarding monitoring, reporting, investigating and prosecuting financial irregularities.