U.S. President Barack Obama on Thursday called his Egyptian counterpart, Mohamed Morsi, to express his "deep concern" about the deaths and injuries ensuing from protests over expanded presidential power and a draft constitution in the Arab country.

"President Obama called President Morsi today to express his deep concern about the deaths and injuries of protesters in Egypt," the White House said, adding that Obama emphasized that all political leaders in Egypt should make clear to their supporters that "violence is unacceptable."

Seven people were killed and more than 770 injured after hours of clashes on Wednesday and early Thursday between Morsi's opponents and supporters outside the presidential palace in Cairo.

The opposition has been demanding Morsi to rescind the decrees granting him nearly unrestricted powers and put on hold a controversial draft constitution the president and his Islamist allies are seeking to put to a referendum slated for Dec. 15.

In a speech on Thursday night, Morsi called for a resolution of political differences through dialogue.

In their phone conversation, Obama welcomed Morsi's call for a dialogue and urged both sides to pursue the dialogue "without preconditions," the White House said.

Obama "underscored that it is essential for Egyptian leaders across the political spectrum to put aside their differences and come together to agree on a path that will move Egypt forward," the White House said.

It said Obama reiterated Washington's "continued support" for the political transition under way in Egypt.