Afterwards, Serbian PM Ivica Dacic thanked Rome for its strong support to Belgrade, calling Italy Serbia's "biggest friend" in the West.
This was the third joint session of the two governments.
We want Serbia to be the 29th European star and will continue to work towards that goal, RTS quoted Letta as saying.
Speaking to the press, he said Serbia could play a key role in the Balkans and that now it was necessary for both Belgrade and Brussels to take the next steps.
The joint government session clearly shows Italian entrepreneurs that Serbia is important for cooperation, said Letta.
Dacic said Italy had become Serbia's main trading partner.
More than 500 Italian companies are active in Serbia, employing about 22,000 workers and generating EUR 2.5 billion annually, mainly in the auto and textile industries.
"We don't want Fiat to close down factories in Italy and work (in Serbia), but to open both here and there," said Dacic.
In the joint company Fiat Automobiles Serbia, which makes FIAT 500 L cars in Serbia for export, the state has a 33 per cent stake and Fiat 67%. The EUR 1 billion factory was opened in April 2012 and has been described as the biggest investment in Serbia in the last few decades.
Dacic said Italian-Serbian economic cooperation was ahead of German-Russian cooperation and that Italy was the country from which Serbia imported and to which it exported the most.
Delegations of the two countries today signed four agreements - on road transport, cooperation in European integration, an Italian Justice Ministry donation to Serbia for an organised crime database, and a protocol on the exchange of information on drug trafficking.