Phillip J Crowley also told that India have the right to take independent decision on the issue.
"So everyone has a responsibility to do what each country can to convince Iran to change its present course. I"ll leave it to India to describe what steps it is going to take," said Crowley.
"By the same token, all countries have international obligations to fully respect and to heed the sanctions that were passed by the Security Council in Jun 2010," he added.
On Monday, 5 Jul Indian Foreign Secretary Nirupama Rao told that unilateral sanctions on Iran can have a direct and adverse impact on Indian companies and more importantly, on India's energy security and attempts to meet the development needs of people.
Commenting on this Crowley told the US understands that every country obviously pursues its own self interest of its citizens.
"We would expect all countries to respect and commit themselves to undertake and to enforce the sanctions that have been passed by the UN Security Council," said State Department spokesman.