"France was chosen to host this big event and will live up to the scale of the task," Hollande said, adding that a smooth running of the world's third biggest sporting event would also showcase a country bidding to host the 2024 Olympics.
"If measures have to be taken tomorrow, they will be taken."
His government chimed in 24 hours ahead of the first match of a month-long soccer fiesta that millions of fans and foreign visitors hope to follow despite an industrial dispute and pickets that have hit public transport and rubbish collection and snarled up strategic roads.
"Some people just don't give a damn that their country is about to host a big event which creates jobs and huge economic benefits," sports minister Thierry Braillard said.
The message fell on deaf ears. The hardline CGT union said it would extend a rubbish collection strike in the capital until June 14 and Air France AIF.PA pilots confirmed a four-day walkout from Saturday after pay talks collapsed.
While rail services improved as a nine-day strike over work and rest time ran out of steam, one union said it might disrupt services and make it hard for fans to reach France's opening match against Romania on Friday.
Air France said it would be have to cancel up to 30 percent of flights during the four-day walkout by pilots but said it hoped to minimize disruption to travel to cities hosting the Euro championship.
"Of course, we'll look after the Euro tournament," airline chief Frederic Gagey told a news conference, adding the dispute would cost the airline 5 million euros ($5.66 million) a day.
Finance Minister Michel Sapin said the confrontation risked undermining a nascent pickup in economic growth after official data suggesting job creation was rising and an unemployment rate of 10 percent starting to drop, a year from elections.
France labour dispute: Trash collection disrupted amid new wave of strikes
"SPANNER IN THE WORKS"
The country has been plagued for weeks by protests over plans to change labor laws, compounded by sectoral disputes over issues such as reorganization of work and rest time at the state-owned SNCF railways.
Hollande says reform is key to tackling unemployment, which he promised to bring down when elected in 2012. Sapin said job creation in the first three months of the year was better than in any quarter since early 2008.
"This is not the moment to throw a spanner into the works, with growth picking up," Sapin said.
As millions of foreign visitors and soccer fans prepared for the soccer tournament, garbage piled up on the streets in parts of Paris, and Marseilles garbage workers started similar action, bringing waste plants to a standstill.
Hours from an opening soccer match that pits France against Romania, a train driver representative of the SUD union warned that travel to the 80,000-capacity stadium could be disrupted on a commuter line known as the RER D. The line usually ferries tens of thousands of fans to the site from inner Paris.
"The Euros are here and let me tell you this, it's going to be hard to take the RER D on Friday," said SUD representative Fabien Villedieu. "They'll find some non-strikers to man trains, but it's going to be complicated to get there by train."
It was not clear that his union had enough power to cause a major disruption through a strike, or whether it planned to set up pickets or even occupy the rail tracks. A representative of the RATP urban transport network said plans were being made to ensure enough trains to get tens of thousands of soccer fans to their destination.