Hi,
I have a foreign bank account. Are interests earned require taxes to be paid when the bank in the foreign country is already withholding taxes?

On your U.S. return, you must report your worldwide income. You will claim credit for taxes paid in the foreign country. Read: Your U.S. Tax Return: U.S. Citizen or Resident with Foreign Income

In the United States, all earned income must, by law, be accounted for. If the foreign country withholds taxes, that would also show on your 1040.
Such taxes paid would then be a legitimate allowance to be deducted from taxes paid to the I.R.S.

Such income, earned abroad, would be subject to taxes by the U.S... and any taxes paid on it would be a deduction. But, if not sufficient taxes paid to the foreign country meet the U.S.'s normal tax rate, you could be hit with further taxes owed by the U.S.

Generally all countries have agreements with Washington about how much can be earned in foreign lands without payment of taxes to Washington.

An example, many Canadians, Snowbirds, spend 6 months in Florida and other southern climes during the winter months. In effect, they are earning money by many avenues, but mostly through pensions and investments, and not a penny is paid in taxes to the U.S.
They are taxed at home... as though they never left.
The U.S. has mentioned many times, it would like to tax these individuals because of the time they spend in the U.S. and no matter how they earn money, they earn it while living in the U.S.
Canada has an agreement with the U.S. about such away from home living and treat each others visitors as not taxable as long as it is not "earned income" in the country so visited.