Lactalis has launched a €1.3bn takeover bid for the company in the hope of creating a new French food giant.
Should the deal be successful it would prize Yoplait, which had global sales of around €4.5bn in 2009, out of the hands of foreign predators, including Nestlé, PepsiCo and General Mills.
Lactalis is the maker of France's flagship camembert brand, President, and in 2009 registered overall sales of €8.5bn.
The bid for Yoplait has surprised some analysts, who had expected Lactalis to launch a joint offer with Nestlé.
It is thought that Lactalis is attempting to present its bid in a patriotic light as a way of keeping Yoplait out of foreign hands.
The French government has previously been roused to action when one of France's most-prized companies, Danone, was rumoured to be subject of a takeover by PepsiCo in 2005.
As a result, the French parliament changed the law, forcing foreign companies to declare their intentions if they were seeking to buy a French company.