"I am fully aware that this is a sensitive time but I am thinking above all of Italy," Letta said at a press conference in Rome as he struggles to lead Italy out of a painful recession.
"I hope the general interest wins over personal interests - for the good of the country," he said.
Reactions from Berlusconi lawmakers were measured, despite protests against a ruling that bars the billionaire tycoon from being running in elections for the next six years after being convicted of tax fraud.
"Silvio Berlusconi's legal woes will not be a problem for the government," said Mara Carfagna, a leading member of Berlusconi's People of Freedom party.
"This anger we all feel must not boil over," she said.
The greater uncertainty is whether Letta will manage to contain growing discontent within his own Democratic Party (PD) about governing together with a coalition led by a confirmed criminal.
Some leftists have called for the 76-year-old Berlusconi to be expelled from the Senate as soon as possible, with the Five Star protest movement calling for an immediate vote on his ousting.
But Alfonso Stile, a law professor at Rome's Sapienza university, said the procedure to exclude him from parliament would be "long and tortuous".
Italy's top court on Thursday handed Berlusconi his first definitive conviction in a 20-year political career dogged by legal woes and sex scandals.
The court ordered the three-time premier to do a year of community service or be placed under house arrest -- a sentence due to be enacted in October.
An embittered and visibly shaken Berlusconi delivered a video message on Italian television late Thursday in which he dismissed the sentence as baseless and vowed to continue his political career.
"It was an extraordinary performance within hours of being convicted on a serious crime," said James Walston, professor at the American University in Rome.
Berlusconi's sentence is still to be determined exactly but his passport will be taken away, he will need court permission to attend parliamentary sessions and even his knighthood could be withdrawn.
Italy's current government was installed following a two-month deadlock between Berlusconi and the their eternal rivals, the PD, after close-run February elections.
The case against Berlusconi revolved around the purchase of film distribution rights by Mediaset - the platform for his first entry into politics.
Berlusconi is still appealing convictions in two separate cases for having sex with an underage prostitute, abusing his prime ministerial powers and leaking a police wiretap to damage a political rival.
Other fraud and bribery charges against him over the years have either been overturned on appeal or have expired under the statute of limitations thanks to Italy's slow-moving justice system.
Berlusconi has been repeatedly written off in the past but re-emerged thanks to his formidable political skills and charisma on the campaign trail.
Walston said the guilty verdict was also unlikely to have any great affect on his mammoth empire, because "there have been much more serious criminals who have run their businesses from inside jail."
But some analysts on Friday predicted his long career in the spotlight was over.
"Starting today, we are beginning a post-Berlusconi Italy," said Stefano Folli, a columnist for the Il Sole 24 Ore business daily.
Marcello Sorgi, writing in La Stampa, said: "His time is over... The question now is not whether Berlusconi will leave the scene or even when but how."
Giovanni Orsina, a politics professor at LUISS university in Rome, was more wary.
"Those who think this story is over or nearing the end are mistaken," he said. "The end will be long and risks being bloody".
Italians reacted with little surprise but underlined the significance of the ruling - Berlusconi's second and final appeal in the seven-year legal case.
"This conviction is important for everyone, not just Berlusconi," said Paolo Grazioli, a 76-year-old pensioner.
"But one thing is for sure - he is not going away to a retirement home."