The surgery was successful and Gentiloni, 62, is well and awake, the officials said, adding that he was likely to remain in hospital for a few days.
“We exchanged messages this morning and I am sure that he will be back at work very soon,” junior minister Benedetto Della Vedova told reporters.
The premier was taken to hospital after complaining of discomfort on his return to Rome from an official visit to Paris on Tuesday, and doctors decided he should undergo an angioplasty.
An angioplasty is a procedure to widen a blocked or narrowed blood vessel, usually an artery.
Gentiloni is conducting a tour of European capitals following his appointment last month to replace Matteo Renzi, who resigned following a crushing referendum defeat.
He was in Paris on Tuesday to meet French President Francois Hollande and had been due to fly to London on Thursday to meet his counterpart Theresa May.
With Hollande, he discussed celebrations to mark the 60th anniversary in March of the Treaty of Rome, the accord that established what would eventually become the European Union.