I am a US resident with a green card. I received an income of $4,000 in india in my indian bank account in early 2010. I filed the tax return in india but had to pay only $80 in tax because I had very little income.
However, I fall in 25% tax bracket in US. Wen I report this income on my US tax return, will I have to pay 25% tax on it or will the DTTA protect me because I have already paid tax on it in india.

You MUST report the interest income on your U.S. return and pay the tax; you can claim a Foreign Tax Credit under "passive income" on Form 1116 for the taxes paid to India.

If tax rate is higher in US than what you paid in India, you will pay the difference in US. However, actual calculation will be on Form 1116.