WASHINGTON - The United States insisted on Monday that there is still "time and space" to end the standoff over Iran's nuclear program, in a subtle rebuttal of Israel's demand for a clear red line.

"We believe that there remains time and space for that effort to bear fruit, an effort that is focused on punitive sanctions to isolate and pressure Iran, and on diplomacy to bring about a change in behavior from Iran," White House spokesman Jay Carney told reporters at a regular news briefing.

He was responding to a query about Israel's demand for a clear red line over the Iranian nuclear program in talks with Washington.

In an interview with a Canadian TV channel aired late Sunday, Israeli Prime Minister Benjamin Netanyahu asserted that "Iran will not stop unless it sees clear determination by the democratic countries of the world and a clear red line."

The prime minister asked for the red line last week on the grounds that the move would avoid war with Iran, as he himself and other Israeli leaders have threatened time and again preemptive air strikes on Iran's nuclear sites to stop the uranium enrichment activities in the Islamic republic.

Washington, however, is in no mood to see an armed conflict over Iran in an election year as President Barack Obama is seeking a second term in November.

Stating that the US and Israel have been engaged in extensive talks over Iran's nuclear program and other security-related issues, Carney reiterated Obama's position that "all options" are on the table in fulfilling his commitment to prevent Iran from acquiring nuclear weapons, a claim vehemently rejected by Tehran which insists on the peaceful nature of its nuclear program.

"And that has not happened," Carney said. "There remains time ... to continue to pursue the two-pronged effort here, a diplomatic push paired with this intense pressure through punitive sanctions and other means that have isolated and pressured the regime in Tehran."

"But, we've also made clear that the window of opportunity for reaching a solution by that means will not remain open indefinitely," he added.

State Department spokeswoman Victoria Nuland also refused to give a direct reply over the issue of red line, saying only "We need to continue to work through these issues, make sure that we are comparing notes on what we are seeing, make sure we are comparing notes on the best way to increase the pressure on Iran to come clean with the international community and come back into compliance."