Safir mingled with movie stars at the Academy Awards ceremony in Los Angeles on Sunday. Giuliani played golf and met with fellow Republicans in Arizona over the weekend.
The timing of the trips angered several City Council members and activists, who said City Hall is out of touch with New York's minority communities.
Safir's office told City Council leaders last week that because of a scheduling conflict, the commissioner could not attend a hearing on the police unit whose members killed Diallo on Feb. 4. But Safir surprised City Council members by showing up for the hearing Monday morning.
Giuliani says it was a weekend, and he and Safir are entitled to take time off.
A grand jury is investigating the Diallo shooting to determine if charges should be filed against the officers, who are on desk duty. Protests have been held almost daily outside police headquarters in lower Manhattan.