The EU late last year launched its more limited "Triton" operation after Italy said it could no longer afford to do the job faced with a tidal wave of migrants from North Africa and Middle East conflict zones.
Italy reported 170,000 migrant arrivals in 2014, up four-fold, while some 3,200 people died at sea trying to reach Europe, according to the International Organisation for Migration.
The situation has deteriorated in recent months, putting the European Union under pressure to do more.
EU Home Affairs Commissioner Dimitris Avramopoulus said the 28-nation bloc would give Italy €13.7 million ($12 million) in direct aid and extend the Triton operation to at least the end of 2015.
The EU was ready to increase aid if need be, Avramopoulus told a press briefing.
"We cannot replace Italy in the management of the external borders but we can lend a helping hand. So we will extend Operation Triton and we will increase its resources if this is what Italy needs."
Some 21 EU member states support Triton but others such as Britain argue that it and other rescue missions exert a "pull factor" which only encourages more migrants to cross the Mediterranean.
Italy halted its larger 'Mare Nostrum' operation in October, complaining that it had spent 114 million euros while its EU peers had failed to shoulder their share of the burden.