"We have an agreement with 3M to provide funds to respond to our demands," Jean-Francois Caparros, the union representative, said.
The factory, which produces pharmaceutical products, employs 235 people but 110 of these jobs are to be shed this year due to falling orders and another 40 are to be shifted to another plant.
The 3M incident follows a similar situation earlier this month involving two bosses of Sony France in the country's southwest, who were freed after they helped secure improved terms for workers facing redundancy.
The country is undergoing a severe economic crisis and two massive public demonstrations have been held in recent weeks.
The labour ministry announced on Wednesday that the number of unemployed people in France had jumped by 79,900 to 2.38 million in February - a smaller rise than the 90,000 who lost their jobs in January.
Earlier Rousselet had said that workers had "more to complain about than me and I knew there was this risk when I came here", and that there was not threat of violence.
There have been several cases of executives being held hostage over the past year by French workers outraged at learning that their jobs were being slashed.
Pelted with eggs
Last week, tyre factory workers burst into a management meeting and pelted their bosses with eggs to protest against the closure of their plant.
The action comes as vandals smashed windows and damaged a car at the home of Sir Fred Goodwin, former Royal Bank of Scotland chief, who sparked public anger in Britain when he refused to give up his large pension after the government rescued his bank.
Police in Edinburgh, the capital of Scotland, said Goodwin's large detached house was attacked in the early hours of Wednesday morning.