The plan hopes to utilize both the Italian military and humanitarian groups, ANSA reported.
Letta released the plan in reaction to the more than 500 migrants feared dead in two boat accidents this month alone.
Navy spokesman Alessandro Busonero said three vessels have been assigned to patrol the Mediterranean. A helicopter and its pilot as well as a regiment of soldiers are aboard the ships.
Italian Defense Minister Mario Mauro said the objective was to "boost three-fold our presence with men and means in the southern area of the Mediterranean for a military-humanitarian mission with the aim of containing the current crisis."
Mauro said the cost of the program had not been determined.
"The problem is not how much it costs," he added. "It is necessary to do it to confront the ongoing humanitarian emergency."
While the government organized the patrols on its own, Letta said he would call on the European Union to provide more assistance during an EU summit later this month.