Some shareholders and clients of the German exchange operator had expected a possible bidding war with rivals Nasdaq OMX
But the source said on Wednesday: There are no plans to increase what Deutsche Boerse has already offered.
Deutsche Boerse's agreed all-share bid to create the world's largest exchange operator was topped last week by a $11.3 billion unsolicited cash and stock offer from Nasdaq OMX/IntercontinentalExchange.
A source close to NYSE Euronext told Reuters in New York on Wednesday a merger between NYSE and Nasdaq would be strategically unattractive and face insurmountable antitrust problems.
The board of the NYSE Euronext, which owns the venerable New York Stock Exchange, plans to meet by April 14 to consider the higher bid, another source familiar with the situation has said.
Deutsche Boerse, which is set to hold its next regular board meeting on April 12, declined to comment.
But even without having to compete with an aggressive rival bidder, Deutsche Boerse's hopes of creating the world's largest financial exchange reliant on derivatives trading will still need to be approved by increasingly nationalistic regulators.
The planned decision by Australia to reject Singapore Exchange Ltd's
Bankers meeting at the Reuters Global Mergers and Acquisitions Summit in London on Wednesday also noted that this was likely to have ramifications for London Stock Exchange's
The noises coming out of Australia yesterday will undoubtedly have a knock-on effect on the Canada/London deal, noted Caroline Silver, a managing director advising financial services companies at independent investment bank Moelis.
Deutsche Boerse shares had stopped trading for the day in Frankfurt before this story was made live.
(Reporting by Luke Jeffs, Editing by Kirstin Ridley, Douwe Miedema and Erica Billingham)