Insurgent commanders "apparently came face to face" with four American officials during meetings on June 3 and June 13 at a villa near Balad, about 25 miles north of Baghdad, The Sunday Times reported.
When asked on NBC's "Meet the Press" about the report of the two meetings, Rumsfeld said: "Oh, I would doubt it. I think there have probably been many more than that."
Under pressure to show progress on Iraq, President Bush appears to be softening his once-firm line against dealing directly with insurgents - now willing to engage something besides military force, CBS News Correspondent Joie Chen reports.
Rumsfeld insisted the talks with insurgents did not involve negotiations with Iraq's most-wanted terrorist, Jordanian-born Abu Musab al-Zarqawi, but were rather facilitating efforts by the Shiite-led government to reach out to minority Sunni Arabs, who are believed to be the driving force behind the insurgency.
In other developments:
The first attack happened when a suicide bomber with explosives hidden beneath watermelons in a pickup truck slammed into a two-story police station near a market at a police headquarters, killing 10 policemen and two civilians and wounding eight more, U.S. Army Capt. Mark Walter said.
Less than two hours later, a suicide bomber blew himself up in a parking lot outside an Iraqi army base, killing 16 and wounding seven more, Walter said. Almost all of the victims were civilian workers arriving at the site, he said.
A third attacker strapped with a belt of explosives walked into Mosul Jumhouri Teaching Hospital and blew himself up in a room for police officers guarding the facility, killing five policemen and wounding 12 others, police Brig. Gen. Wathiq Mohammed Tahr said.
Mosul, the country's third-largest city, is 225 miles northwest of Baghdad and considered an insurgent stronghold. Abu Musab al-Zarqawi's al Qaeda in Iraq claimed responsibility for the attacks. The claim, made on an Internet site used by militants, could not be verified.
Meanwhile, Rumsfeld downplayed the significance of the Sunday Times' report on the meetings with insurgents.
"We see the government of Iraq is sovereign. They're the ones that are reaching out to the people who are not supporting the government," Rumsfeld said on "Meet the Press."
"They're not going to try to bring in the people with blood on their hands, for sure, but they're certainly reaching out continuously, and we help to facilitate those from time to time."