Carter has not confirmed the plans to meet Khaled Mashaal, but Hamas has said the former Democratic president sent an envoy to Damascus requesting a meeting with the militant group's officials.
"I find it hard to understand what is going to be gained by having discussions with Hamas about peace when Hamas is, in fact, the impediment to peace," Rice said at a press event with German Foreign Minister Frank-Walter Steinmeier.
Rice was responding to a question about Carter's plans but did not mention him by name.
"Hamas is a terrorist organization," she said, repeating the Bush administration's explanation for why it will not meet with members of the group.
The State Department says it twice advised Carter against meeting any representative of Hamas. A Carter-Mashaal meeting would be the first public contact in two years between a prominent American figure and Hamas officials.
A press release from the Carter Center said the former president was to lead a study mission to Israel, the West Bank, Egypt, Syria, Saudi Arabia and Jordan as part of his "ongoing effort to support peace, democracy and human rights in the region."
'Efforts to be overshadowed by meeting'
Carter was awarded the Nobel Peace Prize in 2002 for his work in mediating conflicts while in office and his humanitarian travels for the Carter Center since. One of his mediations was the 1978 Camp David Accords between Egypt and Israel, for which Egypt's Anwar Sadat and Israel's Menachem Begin were awarded the 1978 Nobel Peace Prize.
Several Democratic members of the House plan to forward a letter to Carter Monday urging him to reconsider his scheduled meeting with leaders of Hamas during his next visit to the Middle East.
Reps. Artur Davis of Alabama, Shelley Berkley of Nevada, Adam Schiff of California and Adam Smith of Washington state asked Carter to drop the planned meeting.
The letter said "we believe that your efforts to forge peace in the region will be overshadowed by this meeting." It said Carter's meeting could "confer legitimacy" on a group that embraces violence.