Unless you have cashed out your IRA and paid US tax on it, you can not claim the foreign taxes that was withheld by foreign government. You can keep track of the foreign tax that was withheld on your IRA (with applicable supporting statements from your broker) and claim that credit in the year you pay US tax on the IRA withdrawal.

I hope that I have answered your question, if I can be of any help please let me know.

Regards,
Abraham Itani, CPA