Egypt's new president has ordered the police to launch a crackdown on sexual assaults amid growing public anger.
Abdul Fattah al-Sisi also called for citizens to "reinstate moral values in society" after a graphic video of sexual assault victim went viral.
Mr Sisi's inauguration as president on Sunday was marred by a string of sexual assaults on women in Cairo.
Several men have been arrested over the attacks in Tahrir Square, where his supporters were celebrating.
A statement from President Sisi's office said he had told the Interior Minister to ensure there is full implementation of a new law that has for the first time made sexual harassment a crime.
The law decrees that those found guilty of harassment in public or private will face up to five years in prison and a maximum fine of 50,000 Egyptian pounds ($6,990; £4,160).
Activists welcomed the law, but warned it remained to be seen whether it would be enforced by police.
Judicial sources said the arrests that took place after Sunday's attacks were made under the new law.
The Interior Ministry said the men were aged between 15 and 49.
The incidents took place as thousands of supporters of President Sisi gathered in Tahrir Square in Cairo to celebrate his inauguration as president.
The arrests came after a graphic video was posted on YouTube on Sunday showing a badly injured naked woman being dragged through a large crowd towards an ambulance.
It is not clear when it was filmed, but witnesses told the BBC similar assaults had taken place in the square on Sunday night.
A statement released by Mr Sisi said he had told Interior Minister Mohammed Ibrahim to "vigorously enforce the law" to stop sexual assaults, which he described as "an unacceptable form of conduct."
"The president calls on all citizens to undertake their part to reinstate the true spirit of ethical and moral values in Egyptian society," the statement added.
Women's groups say that the new laws have not done enough. On Monday dozens of rights groups accused the government of failing to address the issue.
In a statement, the groups said they had documented more than 250 sexual assaults from November 2012 to January 2014 and called for a "comprehensive national strategy" to stop the violence.
Sexual harassment has long been a problem in Egypt, but assaults have increased dramatically in the three years since Hosni Mubarak was removed from power.
Many of the attacks have taken place in the large crowds that frequently gather in Tahrir Square, the birthplace of the 2011 uprising against Mubarak.