Italian Interior Minister Roberto Maroni struck a deal with Tunisia earlier this month under which migrants who have already arrived will receive permits, but any new arrivals will be deported under a new arrangement. Maroni has accused France of violating the rules of the European Union's Schengen visa-free zone.
The 25-country visa-free Schengen Zone covers most of the EU, but does not include the United Kindgom or Ireland.
French Interior Minister Claude Guéant said France had every right to send the migrants back to Italy.
A total of 25,800 migrants on 390 boats have arrived in Italy so far this year, including around 21,000 who said they were from Tunisia.
France detained 2,800 undocumented Tunisian migrants in March alone said Guéant adding that most had already been sent back to Italy.
Hundreds of the migrants have travelled to the town of Ventimiglia on the French-Italian border in recent weeks and have tried to board trains to the French city of Nice.
Immigration is set to top the agenda at a summit between French President Nicolas Sarkozy and Italian Prime Minister Silvio Berlusconi in Rome on 26 April.