HEILIGENDAMM, Germany — President Bush said it was “a sad day” for I. Lewis “Scooter” Libby and his family when the former top administration aide was sentenced to 2 1/2 years in prison for obstructing a CIA leak investigation.

In making his first public comments on the latest development in the Libby case, Mr. Bush declined to address speculation about whether he might pardon Vice President Cheney’s former chief of staff.

“There’s a ongoing process, and it wouldn’t be appropriate for me to discuss it until the process has run its course,” the president told a group of reporters in Heiligendamm, Germany, where he is attending the annual Group of 8 summit of leaders from the world’s leading industrialized nations.

While a president can issue a pardon without conditions, Justice Department guidelines require the petitioner to wait at least five years after conviction or release from prison before requesting a pardon, according to the department’s Web site.

U.S. District Judge Reggie Walton, who sentenced Libby yesterday, set a June 14 hearing on whether to let him remain free while appealing his conviction, though the judge said he isn’t inclined to do so.

Judge Walton also fined Libby $250,000 and rejected his plea to be spared a prison term for lying to investigators probing the disclosure of Central Intelligence Agency operative Valerie Plame’s identity. Libby, 56, resigned on being indicted in 2005.

Libby was convicted of lying to investigators probing whether the Bush administration deliberately leaked Ms. Plame’s identity to retaliate against her husband, Joseph Wilson, who accused the government of twisting intelligence to justify the 2003 invasion of Iraq.