"We are freezing movement (of personnel) for the time being to analyse the situation so we can adapt our operations," Sky News quoted an ICRC spokesperson as saying.
The announcement came a day after Michael Greub, a 42-year-old Swiss citizen heading the ICRC's office in Libya's Misrata city, was killed by gunmen in Sirte, some 450 km from Tripoli.
Greub had been leaving a meeting with two colleagues when the attackers shot at their vehicle at point-blank range.
"If our aid workers' lives are in danger, we have to try to adapt our structure, our way of working' to protect them," the spokesperson said.
The ICRC has some 30 expatriate staff members and around 150 local staff in Libya.