The meeting was scheduled to take place Thursday in Paris and was one of the highlights of the conservative prime minister's first European visit since being elected.
But Israeli officials accompanying Netanyahu during Tuesday's stop in Rome said that Defense Minister Ehud Barak will instead travel to Washington next week to hold talks with Mitchell.
In a statement read out to reporters, the prime minister's office said the Netanyahu-Mitchell meeting was being postponed until after the talks with Barak in order to "clarify issues."
Netanyahu arrived in Italy on Tuesday, part of a European jaunt that includes stops in Rome and Paris to sound out regional allies about his qualified endorsement of a Palestinian state.
Netanyahu meets first with Premier Silvio Berlusconi, whom he described in a RAI state television interview Monday as "a great friend of Israel, committed to promoting peace and security."
Italian Foreign Minister Franco Frattini, who was attending the meeting, said Italy would ask Netanyahu to quickly open talks with Palestinian President Mahmoud Abbas. He said Italy would also appreciate the "gesture" of a moratorium on expanding existing settlements, the Apcom news agency reported.
Less than two weeks after the Israeli leader finally gave qualified endorsement to the concept of a Palestinian state, Netanyahu will likely be sounding out Berlusconi and French President Nicolas Sarkozy to see if they are on board with the caveats he placed on such a state. These include the demand that it be demilitarized and recognize Israel as a "Jewish state."
In his June 14 speech Netanyahu also said the Palestinians must give up any notion of refugees who left what is now Israel - or their millions of descendants - resettling in their former homes.
Berlusconi's pro-Israel stance has made Italy perhaps Israel's best friend in Europe.
The Italian leader has backed pro-Israel rallies and supported Israel's right to defend itself during its recent armed conflict with Hamas in Gaza - while other European leaders tended to view the hundreds of fatalities Israel caused in its retaliation for rocket attacks as disproportionate.
Foreign Ministry officials said the fact that Netanyahu was making his first stop in Rome was testament to the solid Italian-Israeli ties and Berlusconi's pro-Israel stance.