I have Dividend income from US shares. 25% of the dividend amount is withheld as US tax by the UBS.
How can I claim rebate on income tax in India on this dividend income?

If you are talking about claiming a tax credit on your Indian tax return, that is beyond my skill set.

You MAY want to post this question on the link below:

mytaxes - Index

If you are asking about filing a U.S. tax return to reclaim the taxes, 25% IS the tax rate for ordinary dividends. The tax rate for qualified dividends is 15%. If your dividends were qualified dividends, you need to file to request a refund of the 10% difference. If the dividends are NOT qualified, no filing is required.