Israel has been alarmed by the mounting emphasis on diplomacy with the new Iranian government of President Hassan Rouhani to allay concerns about Tehran's nuclear ambitions, fearing that Western governments may ease crippling sanctions before securing any real policy change.
"As long as we don't see actions but only words, the international pressure must continue and increase," Netanyahu said.
He said that the greater the pressure on Iran, "the higher the chance its military nuclear programme will be dismantled."
The Israeli premier also warned of legitimising what he called Tehran's "rogue regime".
Netanyahu's remarks came as a senior Israeli delegation was on its way to Washington for updates on talks between the major powers and Iran over its nuclear programme which resumed in Geneva on Tuesday.
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Strategic Affairs Minister Yuval Steinitz and a team of officials from intelligence services and the foreign and defence ministries were to participate in the bi-annual strategic dialogue, a statement from his office said.
"This year the dialogue will focus on the nuclear talks with Iran and other regional issues," it said of the meetings which are the "central forum" for deepening bilateral cooperation and coordination over issues in the region.
A spokesman for Steinitz said the minister will make a stop in Canada for talks with senior officials there on Monday before heading to the United States.
Ahead of the visit, a senior Israeli official was briefed by the US as well as a British delegation to the Iran talks, which flew in to update the Israelis, the Haaretz newspaper reported.
French and German officials also briefed their Israeli counterparts by phone on the substance of the Geneva talks, the paper said.
Netanyahu is also due to meet US Secretary of State John Kerry this week in Rome for updates on the P5+1 talks as well as peace negotiations with the Palestinians, the State Department has said.
Israel, which has the Middle East's sole if undeclared nuclear arsenal, has repeatedly threatened to take unilateral action if necessary to keep Iran from developing the capability to build a bomb of its own.