The United States has said it "deplores and condemns" the violence in Egypt.
"We are deeply concerned about attacks on the media and peaceful demonstrators. We repeat our strong call for restraint," White House spokesman Robert Gibbs said.
The call came amid clashes between supporters and opponents of Egyptian President Hosni Mubarak in Cairo.
US state department spokesman PJ Crowley said: "Egypt's path to democratic change must be peaceful."
'Frank and candid'
At the daily White House press briefing, Mr Gibbs said that the transition of power in Egypt must begin immediately and be inclusive of the opposition.
Mr Gibbs noted that President Barack Obama's discussion with the Egyptian leader on Tuesday evening was "frank and candid" and he had received no indication from Mr Mubarak that a crackdown would occur on Wednesday.
When asked if he thought that the Egyptian government had instigated Wednesday's violence, Mr Gibbs replied that he didn't know but emphasised that it must stop.
Mr Gibbs said no decisions had been made with regard to American foreign aid for Egypt, but that the government's actions will be taken into account when reviewing the aid package.
Mr Crowley had earlier sent a series of messages on microblogging site Twitter echoing Mr Gibbs' call for restraint and concern over attacks on the news media.
"The civil society that Egypt wants to build includes a free press," Mr Crowley wrote via Twitter.
"We reiterate our call for all sides in Egypt to show restraint and avoid violence."
Mr Obama issued his strongest statement of support for the protesters on Monday night, saying that an orderly transition of power "must begin now".
His statement came on the heels of Mr Mubarak's announcement that he would not seek re-election.
Mr Mubarak pledged to hold early elections, but did not give a time frame.
Mr Obama said he had spoken to the Egyptian leader after his announcement in Cairo and that Mr Mubarak recognised "that the status quo is not sustainable and a change must take place".
The US president praised Egypt's military "for the professionalism and patriotism that it has shown thus far in allowing peaceful protests while protecting the Egyptian people" and urged it to continue that approach.
He stressed that it was up to the Egyptian people to choose their leaders, and that the US would continue to offer support and friendship to them.