"There's a lot of hysteria about this deal. People really need to look at the facts, and they need to look at the science behind those facts," Kerry told Israel's privately run Channel 10 Television in an interview.
Kerry said a final agreement due to be agreed by June 30 provides indefinite access to Iranian nuclear facilities.
"We will have inspectors in there very single day. That's not a 10-year deal. That's for ever. There have to be inspections," he said.
On Wednesday, Iranian Foreign Minister Mohammad Javad Zarif told an audience at New York University that Tehran is willing to submit to the highest level of international transparency on its nuclear programme and wants to conclude a final accord as soon as possible.
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If fully implemented, a deal will see Iran dramatically scale back its nuclear activities and submit those that remain to what US President Barack Obama has described the "most robust and intrusive inspections and transparency regime ever negotiated".
On April 15, Israel's Prime Minister Benjamin Netanyahu compared Israel's arch-foe Iran to Nazi Germany, and suggested that the lessons of World War II had not been learned.