Olmert said in the interview that was shown on Israeli television: "The most that we tried to get for ourselves is to be able to live without terror. But we never threatened any nation with annihilation.
"Iran, openly, explicitly and publicly threatens to wipe Israel off the map. Can you say that this is the same level, when they are aspiring to have nuclear weapons, as America, France, Israel, Russia?"
Miri Eisen, Olmert's spokeswoman, who accompanied the prime minister on a trip to Germany on Monday, said he did not mean to say that Israel possessed or aspired to acquire nuclear weapons.
She said: "No he wasn't saying anything like that."
Mark Regev, the Israeli foreign ministry spokesman, said that Olmert had meant to categorise the four nations as democracies to set them apart from Iran, and was not referring to their potential nuclear capabilities or aspirations.
Olmert's office said the quote was taken out of context and noted that in other parts of the interview, Olmert refused several times to confirm that Israel has nuclear weapons.
The subject of Israel's nuclear capability was raised last week by Robert Gates, the incoming US defence secretary, who told a Senate confirmation hearing that Israel had atomic weapons.
Gates on Tuesday said that Iran might want an atomic bomb because it is "surrounded by powers with nuclear weapons: Pakistan to their east, the Russians to the north, the Israelis to the west and us [the US] in the Persian Gulf".
The remark led Israeli news bulletins with Israeli state-run radio suggesting that Gates may have breached a US "don't ask, don't tell" policy that dates back to the late 1960s.
Middle East diplomacy
Olmert arrived in Berlin on Monday at the start of a two day visit to Germany and Italy aimed at rallying European support for Israel and censure against Iran.
On his first official trip to both countries since taking office in May, Olmert is to hold talks on Tuesday with Angela Merkel, the German chancellor, and with Romano Prodi, the Italian prime minister, on Wednesday.
He is expected to press both leaders for economic sanctions against Iran, should Tehran refuse to abandon its nuclear programme.
Olmert and Merkel are also expected to discuss the Middle East peace process, Israeli officials said.
Eisin said: "Germany, Italy and Europe in general have a role to play to advance the peace process.
"But there cannot be any recognition of the [Palestinian] Hamas government as long as this movement does not recognise Israel and does not give up its mission to destroy it."