"We are freezing movement (of personnel) for the time being to analyze the situation so we can adapt our operations," ICRC spokesman David-Pierre Marquet told AFP on Thursday.
He said there were no plans to permanently halt the organization's operations in Libya.
The announcement came a day after Michael Greub, a 42-year-old Swiss citizen heading the ICRC's office in Libya's third city Misrata, was killed by gunmen in Sirte, 200 kilometres further along the coast.
Greub had been leaving a meeting with two colleagues when the attackers shot at their vehicle at "point-blank" range, ICRC spokesman Wolde Saugeron said on Wednesday.
Greub's two colleagues emerged unscathed from the attack.
"They were very lucky," Marquet said, noting that the security situation in the country was of deep concern.
Greub's death came just a week after a local 23-year-old Red Cross employee was murdered in Benghazi, he pointed out.
"If our aid workers' lives are in danger, we have to try to adapt our structure, our way of working" to protect them, he said.
The ICRC counts some 30 expatriate staff members and around 150 local staff in Libya.
The organization will surely reduce its footprint somewhat following its evaluation, Marquet said, adding that the aim was to complete the review quickly so operations could resume.
He said the ICRC had been surprised by the attack, since "Sirte is rather calm — it's not like Benghazi — and we received no indication that an incident like this might occur."
Greub and his colleagues were not travelling in a marked vehicle, so it was unclear if ICRC was the intended target or if the attack was random, Marquet said.
"We're trying to understand why this happened," he said.
The neutral, Switzerland-based ICRC specializes in providing aid in conflict zones and overseeing respect for the Geneva Conventions on warfare, such as the treatment of prisoners.
In 2012, it put a temporary freeze on operations in Misrata and the eastern city of Benghazi after unidentified gunmen attacked its Misrata compound.
There were no casualties in that attack.