After a tense weekend, the diplomat sought to quell any speculation of a full-blown crisis, saying that no criticism had come from the U.S. secretary of state.
"Who criticized?" said Italian Foreign Minister Franco Frattini, answering to reporters in Brussels. "Certainly not Hillary Clinton. Let's not create confusion."
Clinton herself, speaking Sunday, said she had not looked into the case but would meet with anybody who had concerns. She said she had not expressed concerns to the Italian government.
Knox was convicted over the weekend of sexually assaulting and murdering her British roommate, Meredith Kercher, and sentenced to 26 years in jail.
Her co-defendant in the trial and former boyfriend, Raffaele Sollecito of Italy, was found guilty of the same charges and sentenced to 25 years in prison. All were studying in Perugia at the time of the 2007 slaying.
Knox and Sollecito have already been kept behind bars since shortly after the killing. They have maintained their innocence and plan to appeal.
The jury in Perugia has not issued the motivations and rationale for their ruling, but must do so within the next 90 days.
The verdict shocked the Knox family and other supporters of the 22-year-old from Seattle. They said evidence was scant and blamed the decision largely on the prosecutors' character assassination of Knox.
Sen. Maria Cantwell, a Democrat from Washington state, said in a statement that she had "serious questions about the Italian justice system and whether anti-Americanism tainted this trial." She didn't mention that Knox's co-defendant was an Italian.
She said that "other flaws in the Italian justice system on display in this case" included negligent handling of evidence and harsh treatment of Knox after her arrest, a charge the Italian police have denied.
Many noted that the jury, two judges and six civilians, had not been sequestered during the yearlong trial, and could therefore be influenced by any unfavorable coverage of the woman.
Media coverage of the case has been intense since Kercher's body was found in a pool of blood on Nov. 2, 2007, in the apartment she shared with Knox.
More on the Amanda Knox Trial:
48 Hours: American Girl, Italian Murder
Knox Family Wants U.S. Gov't Involved
Amanda Knox Visited in Prison by Family
Amanda Knox Found Guilty of Murder
Photo Essay: Verdict In Italy
Amanda Knox: I am Not a Killer
Knox's Lawyer Cries in Court
Saturday's verdict was delivered in the middle of the night in a packed, tension-filled courtroom, with hundreds of cameras and photographers assembled outside the tribunal.
Knox has alternately been depicted as a cold-blooded "she-devil" or as a clean-faced innocent foreigner who fell victim of a poor justice system. Back in the United States, the coverage has been largely favorable to the American and critical of the Italian handling of the case.
Lawyers say that misunderstandings were at least partially due to differences between the U.S. and Italian justice systems.
For example, the Italian system gives the presiding judge a great deal of discretion over the use of circumstantial evidence, said a criminal lawyer, Manrico Collaza. But he noted that allowing the next level of appeal, as Italy does, to deal with the facts of the case - and not be limited to issues of law - acts as balance.
"Many defendants have been saved by it," Collaza said.
Massimo Consolini, an expert on international law, pointed out that criticism of the Italian judicial system has centered on the length of trials that has led to many cases of charges being dropped because of a statute of limitations.
"It's not that one doesn't get a fair trial," he said. It's about "how long it takes to get justice."
He said "the prospects are good" for Knox to win a change on appeal.
However, it will be months before the appeals can open, and even longer to complete. Depending on when that happens, Knox and Sollecito will have spent possibly around three years in jail by then. (Sollecito was moved to a new prison in Terni on Monday, said one of his attorneys, Luca Maori.)
Knox was "tranquil" when she was visited Monday by some family members, said one of her lawyers, Luciano Ghirga. She has asked for permission to work in the prison laundry, and also intends to continue her education by pursuing correspondence courses with the University of Washington, the lawyer told The Associated Press.
"There's a bunch of people that are going home and they would like to see her before they go home but it's not going to happen," Edda Mellas, mother of the American convict, told CBS News outside the jail.
"Like everyone else, she is devastated. She was really hopeful," Mellas told "Early Show" co-anchor Harry Smith of the verdict, speaking by phone after visiting her daughter during the weekend.
"We're all crushed, but she got a lot of loving support when she got back to the jail from inmates and guards, all very supportive of her. And then we got to see her, she got to see her family. We told her to have courage," added Mellas.
Some in Italy were annoyed by criticism in the U.S. media and fired back.
Corriere della Sera, the country's leading newspaper, noted Monday that in America, "the passport is more important than an alibi."
"The (U.S.) administration cannot close Guantanamo, yet it finds the time to think about Perugia," the newspaper said.
Other cases in the past have stirred tension between the two countries, including the 2005 shooting death of an Italian intelligence officer in Iraq at the hands of a U.S. soldier.
In 1998, after a U.S. Marine jet sliced a ski gondola's cables in northern Italy killing 20 people, a U.S. military jury acquitted the pilot of manslaughter. (The pilot was later sentenced to six months in jail and was dismissed from the Marines for helping to destroy a videotape of the flight.)
More recently, an Italian court convicted in absentia 23 Americans - most of them CIA agents - on charges of kidnapping an Egyptian terror suspect.