The White House hopeful Barack Obama says an air strike on Iran will not halt its nuclear program, calling for tougher Iran sanctions.

"Iran is a big country. They have dispersed their nuclear capabilities in a way that you are not going to see smooth, surgical strikes solving the problem entirely the way that Israel was able to deal with Iraq's nuclear threat," he told ABC News.

The Illinois senator called for "tough sanctions" coupled with "tough diplomacy that makes the calculus for the Iranians different."

While insisting that "war is not a good option," Obama maintained that he "would not take military options off the table when it comes to Iran and dealing with their nuclear capacity.”

The US has set a two-week deadline for Tehran to halt its nuclear program, after their talks on Iran's nuclear program.

Envoys from the five permanent members of the UN Security Council--China, Russia, the US, Britain and France--plus Germany held a meeting in Geneva on Saturday to discuss Iran's nuclear program.

MGH/RE