The conference is scheduled for September, but a Defence Department spokeswoman could not immediately provide any specifics about Rumsfeld's move to block France from taking part in the gathering.
"It is his decision. We'll respect it," the French Ambassador to Washington Jean-David Levitte curtly told CNN television.
Downplaying Rumsfeld’s decision, Levitte said “bilateral relations had improved” since the bitter spat following France’s opposition to the US invasion of Iraq.
He attributed the improvement mainly to a meeting between French President Jacques Chirac and his US counterpart George W Bush, earlier in June at the Group of Eight summit in Evian, France, where the two leaders decided to put their differences aside.
The ambassador said the US failure so far to find suspected Iraqi weapons of mass destruction (WMD) had underscored the credibility of UN weapons inspections.
If at all, it would be preferable for the UN team to send its team to Iran and North Korea for an assessment, he said.
The US decision not to invite France reflects the underlying tension between the two countries. At the recent air show in Paris, Washington diluted its participation and private US aerospace companies had just a token presence.