"We are ready to take this to an international court, notably the WTO, because the national tax on digital companies touches U.S. companies in the same way as EU or French companies or Chinese. It is not discriminatory," Finance Minister Bruno Le Maire told France 3 television.
Paris has long complained about U.S. digital companies not paying enough tax on revenues earned in France.
In July, the French government decided to apply a 3% levy on revenue from digital services earned in France by firms with more than 25 million euros in French revenue and 750 million euros ($845 million) worldwide.
It is due to kick in retroactively from the start of 2019.
Washington is threatening to retaliate with heavy duties on imports of French champagne, cheeses and luxury handbags, but France and the European Union say they are ready to retaliate in turn if Trump carries out the threat.
Le Maire said France was willing to discuss a global digital tax with the United States at the Organisation for Economic Cooperation and Development (OECD), but that such a tax could not be optional for internet companies.
"If there is agreement at the OECD, all the better, then we will finally have a global digital tax. If there is no agreement at OECD level, we will restart talks at EU level," Le Maire said.
He added that new EU Commissioner for Economy Paolo Gentiloni had already proposed to restart such talks.
France pushed ahead with its digital tax after EU member states, under the previous executive European Commission, failed to agree on a levy valid across the bloc after opposition from Ireland, Denmark, Sweden and Finland.
The new European Commission assumed office on Dec. 1.
(Reporting by Geert De Clercq; Editing by Edmund Blair and Timothy Heritage)