"The Americans are not ready to allow us to attack Iran," Barak told army radio. "Our position is that no option is to be taken off the table but in the meantime we have to make diplomatic progress."
Israel, the region's sole if undeclared nuclear power, considers Iran its main strategic threat because of its nuclear programme, which Israel and its US ally suspect is aimed at developing weapons.
Iran has repeatedly denied the allegations, insisting its the programme is aimed solely at providing electricity for its growing population when its fossils fuels run out.
Israel's Haaretz newspaper reported that Washington recently rejected an Israeli request for military equipment that US officials said indicated Israel was at the "advanced stages" of preparing an attack.
Washington urged Israel not to strike Iran's nuclear facilities, warning that it would undermine US interests and demanding to know ahead of time if Israel decided to go ahead regardless, the paper said.
Barak did not mention the Haaretz report but said the US government's position was "well known."
"The only thing to do is to continue to act in the field of intelligence and to strengthen economic sanctions against the government of (President Mahmoud) Ahmadinejad," Barak said.
Senior US, European, and Iranian diplomats held rare face-to-face talks in Geneva last month aimed at resolving the impasse over Tehran's nuclear ambitions, but were unable to agree on a deal to resolve the dispute.
