"I think you can intervene immediately by asking Nato vessels already along the Libyan coast to block goods from entering, to also be used to block people from leaving," Italian interior minister Roberto Maroni told reporters on Friday at a security conference in the northern Italian city of Varese.
"This can be done right away if Nato decides agrees. It would be a solution to the problem.
Prime minister Silvio Berlusconi needs votes from Maroni's anti-immigrant Northern League party to keep his government from falling. The Northern League has threatened to end its governing alliance if Italy doesn't pull its support for bombing the North African country.
Unrest in many Arab countries this year has caused the main flow of illegal immigrants seeking to enter the European Union to switch from Greece to Italy's islands, the EU's border protection agency Frontex said Tuesday.
Most migrants arrive in Italy by landing on the small island of Lampedusa, which is closer to Tunisia than the Italian mainland. In excess of 41,000 migrants have reached Lampedusa this year.
Italy on Friday was due to sign an accord with Libyan rebel leaders aiming to keep migrant boats from leaving for Italy. An agreement to jointly patrol coastal waters with Libya was scrapped in March when Italy joined Nato in its mission to defend civilians against Muammar Gaddafi.