Netanyahu was unrepentant as he met with ministers at Israel's weekly cabinet session.
"In the coming weeks, the world powers are likely to reach a framework agreement with Iran which is likely to let Iran remain a nuclear threshold state, something which will first and foremost endanger the existence of Israel," he said in remarks relayed by his office.
"As prime minister of Israel, I am obliged to make every effort to prevent Iran from obtaining nuclear weapons which it will aim at the State of Israel.
"I will go wherever I am invited to make Israel's position heard and to protect its future and its existence," he said.
Last week, Netanyahu said he would be addressing a joint session of Congress on the alleged Iranian nuclear threat on March 3, two weeks ahead of snap elections in Israel.
The invitation was extended by House Speaker John Boehner, a Republican and prominent adversary of US President Barack Obama, and it was not coordinated with the White House in a radical departure from protocol.
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The move reportedly infuriated the Obama administration, with officials saying he would not meet with Netanyahu, citing the proximity of the Israeli elections.
The Obama administration fears Netanyahu's address, focusing on Iran, could be used by the Republicans -- who control Congress -- to undermine ongoing nuclear talks with Tehran at a critical time.
The White House initially gave an icy response to news of Netanyahu's trip, saying it had not been informed -- a break with protocol.
The Obama administration then announced that neither the president nor his Secretary of State John Kerry would meet Netanyahu.
At the heart of the issue is a major foreign policy dispute between the Obama administration and the Republicans over how to handle Iran.
Israel has made no secret of its support for a Republican push for tougher action on Tehran.
Washington and Israel have had several high-profile disputes over how to handle Iran's civilian nuclear programme, which the West believes is a front for building weapons -- a charge Tehran denies.