US secretary of state John Kerry will visit Egypt a day before deposed Islamist president Mohamed Morsi goes on trial.
The Monday court case is the next likely flashpoint in the struggle between his Muslim Brotherhood and the army-backed interim government.
Several hundred Islamists protested in a number of cities today, responding to a call from a pro-Morsi alliance for daily protests until the ousted president stands trial.
In Alexandria, seven people were wounded after residents clashed with Morsi supporters before security forces intervened, a security official said. Forty-five Morsi supporters were arrested. Fighting also erupted in the Gisr al-Suez district of Cairo.
Ties between Washington and strategic ally Cairo have deteriorated since the overthrow of Mr Morsi, Egypt's first democratically elected president. The state news agency said Mr Kerry's visit to Egypt, the first since Mr Morsi's fall, would only last several hours.
A mass uprising which toppled authoritarian ruler Hosni Mubarak, a longtime US ally, in February 2011 had raised hopes that military men would no longer dominate Egypt.
But the man who removed Mr Morsi, army chief General Abdel Fattah al-Sisi, has become a wildly popular figure and many Egyptians have turned against the Brotherhood and anyone perceived as its supporter, including the United States.
State-run newspapers often carry conspiracy theories which suggest Washington backed the Brotherhood to ensure US domination of Egypt and the rest of the Middle East. One even reported that president Barack Obama is a Brotherhood member.
Those dynamics could make it difficult for Washington to lobby successfully for democracy in Egypt.
In a sign of the tension, the United States has said it would withhold deliveries of tanks, fighter aircraft, helicopters and missiles, as well as $260 million in cash aid to Egypt, pending progress on democracy and human rights.
Mr Morsi's removal has posed a dilemma for Mr Obama in dealing with a longstanding strategic ally. He wants to maintain ties with the most populous Arab country, which has a peace treaty with Israel and controls the Suez Canal waterway linking Europe and Asia.
But he does not want to be seen as acquiescing in the ouster of an elected leader, even an Islamist Washington came to view as ineffective during his turbulent year in office.
Washington has repeatedly urged the army-backed interim authorities to govern in a more inclusive manner - code for accommodating the Brotherhood and restoring democratic rule.
It has instead taken harsher measures against Egypt’s oldest Islamist movement. Hundreds of Islamists have been killed and the Brotherhood’s leaders are behind bars, leading to fears that some members of the group will take up arms against the state.
The Brotherhood and its allies have urged crowds to gather on Monday outside a police institute near Cairo’s notorious Tora prison, where Mr Morsi’s trial is expected to take place.
The charges relate to the deaths of about a dozen people in clashes outside the presidential palace in December after Mr Morsi enraged his opponents with a decree expanding his powers.
Reuters