"Italy is close to Libya, not out ahead of it, and will help it to resist foreign interference," Trenta told journalists after returning to Italy from Libya.
"We do not believe that an acceleration of the electoral process can bring stability," she said, adding that the north African nation also needed "reconciliation, the return of security and political work".
The statement appears at odds with French efforts to get conflict-wracked Libya to hold elections in December.
Rival Libyan leaders agreed to a Paris-brokered deal in May to hold a nationwide poll by the end of the year, but scepticism remains high as to whether the country is ready for such a vote.
Trenta held talks with the head of Libya's UN-backed government in Tripoli Fayez al-Sarraj a day after France's top diplomat Jean-Yves Le Drian visited the country to push Paris' initiative.
Former colonial power Italy has close ties to Libya and is deeply involved in efforts to stabilize it after years of chaos following the 2011 ouster of Moamer Kadhafi.
Rome is particularly keen to stem the flow of migrants making the perilous journey to Europe from Libya across the Mediterranean.
Seven years since dictator Kadhafi was toppled and killed in a NATO-backed uprising, Libya remains divided, with rival administrations in Tripoli and the east of the country.
The internationally backed administration in Tripoli said in a statement that Trenta had "reiterated Italy's support for national reconciliation in Libya".
The talks also focused on cooperation over curbing illegal migration, a Libyan spokesman said.