"There is no such thing as 'too big to jail'," Holder said while investigations continue into alleged tax evasion and money laundering by European banks.
Separately, a senior US official told AFP on condition of anonymity that investigations into Switzerland's second largest bank and BNP Paribas were expected to result in criminal charges.
Holder did not cite the French and Swiss banking giants by name, but his weekly audio message warned that the US Justice Department would "follow the facts wherever they lead."
US law enforcement and regulatory authorities have been criticized since the financial crisis of 2008 for not bringing criminal charges against some institutions and individuals accused of fraud.
But Holder, whose department oversees the FBI and its financial crimes task force, denied that the United States was unwilling to prosecute the pillars of the international banking system.
He rejected "the theory that certain financial institutions . . . should be considered immune from prosecution due to their sheer size and their influence on the economy."
And he underlined: "To be clear: no individual or company, no matter how large or how profitable, is above the law."
Holder said: "When laws indeed appear to have been broken — and the evidence supports the allegations — a company's size will never be a shield from prosecution or penalty."
Credit Suisse — which fell more than 2.3 percent on the Swiss stock exchange on Monday — faces a separate inquiry into claims that it helped US citizens evade taxation by sheltering their funds abroad, he added.
BNP Paribas is under investigation over allegations of money-laundering and of breaching US financial sanctions against certain third parties, the senior US official told AFP.
"While I will not specify any particular targets, I will say this: I am personally monitoring the status of these ongoing investigations, I am resolved to see them through," Holder said.
"And in doing so, I intend to reaffirm the principle that no individual, no entity that does harm to our economy is ever above the law."
The US official said formal charges could be brought "in the near future" and probably within "a few weeks."
Investigations are understood to be in their final stages.
Press reports have suggested that Credit Suisse could find itself facing a greater fine than the $780 million that its fellow Swiss rival UBS paid to US authorities in 2009.
The Wall Street Journal reported that according to its sources the bank will pay a fine of between 900 million and 1.4 million francs.
The probe carried out by the Justice Department, the Treasury and financial services regulators in New York must determine if BNP Paribas, as well as French banks Crédit Agricole and Société Générale, laundered money and broke US embargoes by doing business with countries such as Cuba and Iran, a source close to the investigation said.
According to the Wall Street Journal, BNP Paribas is in talks with US authorities to reach an out of court settlement.