Foreign Minister Sheikh Abdullah bin Zayed al Nahyan said the killings underlined the need for greater support for Libya's beleaguered internationally recognised government, which was ousted from the capital Tripoli last August.
His comments came as Egyptian warplanes launched at least seven strikes against targets in the militant stronghold of Derna in eastern Libya.
The UAE "supports, with all its capabilities, Egypt's efforts in eradicating terrorism and violence directed at its nationals and affirms its position in standing alongside and its complete solidarity with it," Sheikh Abdullah told the official WAM news agency.
"The criminals must strongly and decisively receive the punishment they deserve without any hesitancy," he added.
The UAE carried out air strikes from Egyptian bases last year in an abortive attempt to prevent Tripoli's fall to militants, the US military said.
The Gulf state is a member of a US-led coalition waging a campaign of air raids targeting IS in Syria.
It suspended its participation in those sorties after a Jordanian pilot was captured by the militants in December, but resumed operations last week after IS posted a video on the Internet of the airman's gruesome burning alive.
Saudi Arabia's cabinet voiced "strong condemnation of the criminal act by the terrorist" IS group, in a statement published by the official SPA news agency.
Qatar, accused of supporting militants in Libya, condemned "the unacceptable crime that took place" there, in a statement published by the official QNA news agency.
Bahrain's King Hamad denounced the "heinous crime of the terrorist" IS group which "contradicts all religions and human values".
He pledged his support for Egypt "in all measures it takes against this terrorist group" and said Bahrain was committed to "participating with the international community in uprooting terrorism".
On Sunday, Bahrain deployed warplanes to Jordan in support of the air campaign against IS, one week after the Emirati aircraft returned to the fray.
Kuwait and Oman, the other members of the six-nation Gulf Cooperation Council, also officially condemned the beheadings in Libya.
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