The United States believes there is still "time and space" for its two-track approach of diplomacy and pressure to work toward the resolution of Iran's controversial nuclear program, the State Department said on Friday.

In response to press reports about Israel's imminent strike on Iran, department spokesman Mark Toner said that as "unprecedented" pressure has been placed on Iran, "we believe there's still time and space to pursue diplomacy and to allow the sanctions that are in place ... to take hold."

"These are unprecedented sanctions that I think everyone agrees are having a chilling effect on the Iranian economy," he told reporters at a regular news briefing.

An article carried by the Washington Post on Thursday quoted U. S. Defense Secretary Leon Panetta as saying that Israel could attack Iran as soon as this spring.

"Panetta believes there is a strong likelihood that Israel will strike Iran in April, May or June before Iran enters what Israelis described as a 'zone of immunity' to commence building a nuclear bomb," the article said.

It said both Panetta and President Barack Obama "are said to have cautioned the Israelis that the United States opposes an attack, believing that it would derail an increasingly successful international economic sanctions program and other non-military efforts to stop Iran from crossing the threshold."

Israeli Defense Minister Ehud Barak said the same day that if sanctions on Iran do not prove effective, Israel will consider initiating military action to thwart the Islamic republic's nuclear program.