Mark Regev, a spokesman for the Israeli foreign ministry, said on Sunday that Livni had never finalised details for her trip, but stopped making plans after learning that two legislators from Hamas, the Palestinian ruling party, would be attending the convention.
Regev said the ministry had instead sent Yaacov Hadas, its deputy director for Middle East affairs, to the conference.
Roii Rosemblit, the head of Israel's trade office in Doha, said that Hadas would head a delegation of three to four members to the gathering.
Regev said Hamas should not be given legitimacy until it meets demands to recognise Israel and renounce violence.
Israel, backed by the West, has boycotted Hamas, which won Palestinian elections in January. Hamas refuses to recognise Israel and its charter calls for the destruction of Israel.
Israel has low-level ties with Qatar, and Livni's invitation to a United Nations convention on democracy would have been the first visit by a leading Israeli government minister to the Gulf state in a decade.
The last Israeli leader to visit Qatar was Shimon Peres who opened a trade office in 1996.