Cairo (CNN) -- Egypt's Higher Constitutional Court on Tuesday halted the decision by newly elected President Mohamed Morsy to call the nation's parliament back into session, an official said.
The court also "affirmed its rule to dissolve parliament and considers it invalid," said Aly Hassan, a judicial consultant affiliated with Egypt's Justice Ministry.
The ruling is the latest move in a power struggle between Morsy and the country's military rulers, who dissolved the legislature last month.
The parliament, recalled by Morsy, convened for less than an hour Tuesday. The session was the first since the nation's highest court said parliamentary elections were unconstitutional, prompting the military to disband the body.
Morsey, who took office June 30, opted to override the edict of the military, which has run the country since the 2011 revolution that ousted longtime leader Hosni Mubarak.
After the brief session, several hundred demonstrators amassed outside the administrative court in Cairo, which was to address 25 cases filed by individuals protesting Morsy's decision to reinstate parliament. The crowd, which supports Morsy's decision, chanted and hurled water bottles as they stared down more than 100 armor-clad riot police.
The crowd dispersed peacefully, however, after hearing news that the decisions on the cases were postponed for a week. The court is the only one that can overturn a presidential decree.
Lawmakers were divided at the parliamentary session.
Abdul Salam Bashandy, a member of the president's Freedom and Justice Party, said it "filled a legislative vacuum in the country."
But Fathi Desouki of the Egyptian Democratic Party saw it differently.
"The president's decree created a crisis," he said. "We are witnessing a huge power struggle."
Meanwhile, the Muslim Brotherhood, the country's leading political group, called for a million-man protest Tuesday in support of Morsy's decision, said Ahmed Sobea, spokesman for the FJP. It wasn't immediately clear whether the protest took place.
U.S. Secretary of State Hillary Clinton, who will be in Egypt later this week, said democracy can be a messy business.
"We've seen over the last few days that there is a lot of work ahead for Egypt to keep this transition on course," she told reporters Tuesday. "Democracy really is about empowering citizens to determine the direction of their own country."
The military and Egypt's highest court both stuck to their positions on the issue Monday.
The Higher Constitutional Court declared after a Monday meeting that its "ruling to dissolve parliament is final and binding." The court threw out the parliamentary vote in June, prompting Egypt's military to assume legislative power.
And the Supreme Council of the Armed Forces defended its stance, saying it had only acted on behalf of the court ruling.
"We are confident that all state institutions will respect what was issued in all constitutional declarations," SCAF said in a statement that was read by an anchor on state TV.
Despite their opposing positions, the likelihood of a full-blown, open confrontation between Morsy and the country's military rulers is low, said Monique El-Faizy, a project leader at the World Policy Institute.
Both sides have too much to lose and neither can risk pushing the other too far, she said. The showdown will be of the Cold War variety, she predicted.
"I think it's the delicate balancing act that we're going to see for a while," said El-Faizy. "This is all new. Everybody's finding their way."
The crisis was triggered last month when the Supreme Constitutional Court ruled a law regulating parliamentary elections to be invalid.
Parliament had been in session for just over four months at the time. It is dominated by Islamists, a group long viewed with suspicion by the military.
The Supreme Council of the Armed Forces then said it had full legislative power.
Showing no obvious signs of strain, Morsy appeared Monday alongside the head of the SCAF, Mohamed Hussein Tantawi, at a military graduation ceremony in Cairo.
Morsy's recalling of parliament is likely to please his backers in the Muslim Brotherhood, which won the largest share of seats in parliament in elections this year.
Dozens of riot police and barriers surrounded the parliamentary building, but guards there allowed lawmakers into the building Monday, Egypt's state-run Nile TV reported.
Morsy took the helm of a deeply divided nation that is economically strapped and lacks a working government. He quickly indicated that Egypt's legislative power would return to civilian hands -- and while praising the generals, he said their job was "to protect the boundaries and security of the country."
Hassan said that as president, Morsy "has the authority to take any decision, regardless if it's right or wrong."
But, he added, "Overturning the constitutional court ruling and reinstating parliament is against the constitution, especially that there is no appeal on such court rulings."
Journalist Mohamed Fadel Fahmy and CNN's Yousuf Basil and Salma Abdelaziz contributed to this report.