WASHINGTON (Reuters) - President Barack Obama said on Sunday he told the chiefs of the biggest U.S. banks that bonuses are not acceptable while many Americans struggle to meet basic expenses in the midst of a severe recession. Referring to a meeting Friday at the White House with the chief executives of banks that have received U.S. government bailout funds, Obama said bankers need to show some restraint from big bonuses during the financial crisis. "That's just not acceptable," Obama said during an interview on CBS television's "Face the Nation." He said he told the chief executives: "Show some restraint....