The U.S. regards it as "not prudent" for Israel to launch a military strike now against Iran to stop its nuclear program while diplomacy is effective, Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff, said on Sunday.

During an interview with the U.S. TV news network CNN, Dempsey revealed that U.S. officials had tried to persuade Israel to refrain from launching an attack on Iran at present moment to prevent it from acquiring a nuclear weapon.

"That's been our counsel to our allies, the Israelis," he said. "We also know, or believe we know, that the Iranian regime has not decided that they will embark on the efforts to weaponize their nuclear capability."

U.S. officials believe Iran is "a rational actor" and "the current path that we're on is the most prudent at this point," Dempsey said, noting that the economic sanctions on Iran are " beginning to have an effect."

The top U.S. military officer said that, during his trip to Israel later last month, he had "candid conversations" with senior Israeli leaders over the Iran nuclear standoff.

But Dempsey refused to say if he had succeeded in persuading the Israelis to refrain from taking unilateral military actions against Iran without notifying the U.S. "I wouldn't suggest, sitting here today, that we've persuaded them that our view is the correct view," he said.

"I'm confident that they understand our concerns that a strike at this point would be destabilizing and wouldn't achieve their long-term objectives," he said.

Dempsey said that, while Israel has the capability to strike Iran and delay the capability of Iran to achieve a nuclear weapons status probably for a couple of years, some of the targets are probably beyond Israel's reach.

Meanwhile, Dempsey did not rule out the military option to prevent Iran from acquiring a nuclear weapons, vowing that the U.S. military will have all options available "should the nation decide to do something in Iran".

"I mean, fundamentally, we have to be prepared. And that includes, for the most part, at this point, being prepared defensively," he said.

As tensions over Iran's nuclear program rise, the U.S. has tightened economic sanctions on Iran recently, while trying hard to prevent Israel from launching a military strike on Iran that could have destabilizing effects in the Middle East.

When asked if Israel is determined to attack Iran during an interview with a U.S. TV network on Feb. 5, U.S. President Barack Obama said he didn't think that Israel had made such decision, adding that the U.S. and Israel will work "in lockstep" on dealing with the Iranian nuclear standoff.