The Australian Competition and Consumer Commission's airing of its concerns in a statement on its Web site follow the recent decision of the US Department of Justice to oppose Oracle's bid.
Oracle has indicated that it intends to appeal the Department's ruling.
ACCC chairman, Graeme Samuel, said if the acquisition was to go through, it would have "wide ranging international consequences".
"The ACCC has contacted many Australian organisations, both public and private, which use enterprise application software. A significant number of these organisations have stated that the proposed acquisition will restrict their choices significantly and lower the level of competition, especially in relation to complex financial management software and human resource management software," said Samuel.
The ACCC says there are "significant" barriers for other software providers to compete with Oracle and Peoplesoft, as Samuel states "the software requirements of some organisations are very complex and it is not possible for the smaller software companies to meet these needs."
The US courts are scheduled to resume the case this Friday.
