The attackers, apparantely part of a group of around 15 Brotherhood supporters, used birdshot and targeted the tourists while they entered the hotel on Al-Haram Street, the official said.
No casualties have been reported, however. But the attack caused some damages to the bus and the hotel gate and facade.
A suspect was arrested and police were searching for the rest of the group, the Interior Ministry said in a statement.
The attack on the tourists came on a day when Egypt's Coptic Orthodox Christians were celebrating Christmas in the predominantly Muslim country.
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Egypt's security forces have been battling insurgency in North Sinai, which has witnessed many violent attacks by militants since the January 2011 revolution that toppled president Hosni Mubarak.
The attacks targeting police and military increased after the ouster of Islamist president Mohamed Morsi in 2013 by military following massive protests against his rule.
More than 600 security personnel have been reported killed since then.
Al-Haram Street in Giza, close to the Pyramids, regularly witnesses pro-Morsi rallies and protests.