A crowd of angry supporters of President Hosni Mubarak circled around Cooper and his crew, hit him on the head four times and threw bottles and water at them, according to an interview with him posted on the Huffington Post.
"They were following us, screaming at us, ripping at our clothes," Cooper told the Huffington Post. "I've never been punched in the head before. So they left an impression."
Cooper was one of dozens of local and international journalists attacked during the protests, according to Reporters Without Borders.
The attacks on journalists came as thousands of pro- and anti-government demonstrators clashed during protests in Cairo Wednesday, despite calls by the Egyptian army to end the demonstrations and restore order.
Christiane Amanpour, who has covered numerous crises around the world and now works for ABC News, also came under attack Wednesday in Cairo.
After she and her crew realized the situation was becoming dangerous, they tried to leave but angry protesters attacked their car, banging on the sides and windows. One threw a rock that broke a window and shattered glass on the journalists. They managed to escape unhurt.
A CBC News crew tried to photograph Wednesday's violence that erupted between protesters and Mubarak supporters, but they were "marched back to their hotel at gunpoint," according to CBC News' Lara Logan.
"For the first time in the last few days, we can feel what dictatorship really means," she told AP.
They were not allowed to leave their hotel with their cameras and were monitored wherever they went.
An Al Arabiya reporter was in intensive care after being attacked by pro-Mubarak demonstrators and two journalists were still being held Wednesday night, according to a press release by Human Rights Watch.
“The United States denounces these attacks and calls on all engaged in demonstrations currently taking place in Egypt to do so peacefully,” said Philip J. Crowley, assistant secretary of state for public affairs, as reported in The New York Times. “The use of violence to intimidate the Egyptian people must stop.”
The Committee to Project Journalists called the acts "deliberate."
“The Egyptian government is employing a strategy of eliminating witnesses to their actions” in a “series of deliberate attacks on journalists,” said CPJ's Mohamed Abdel Dayem.
Watch this video of the attack on Anderson Cooper:
Read more from GlobalPost on the protests in Egypt:
Follow GlobalPost on Twitter: @GlobalPost