Crowds took to the streets on Friday to protest against the court's decision
Turkey's ruling AK Party has attacked the Constitutional Court over a ruling on headscarves.
The court blocked moves which would have allowed headscarves to be worn at universities. Judges said the move violated Turkey's secular principles.
But AK Party deputy chairman Dengir Mir Mehmet Firat said the court had itself breached the constitution.
He said it was authorised only to examine laws passed by parliament, not rule on their contents.
He was speaking after Prime Minister Recep Tayyip Erdogan chaired a six-hour emergency meeting of top party members.
"The decision is a direct interference with parliament's authority," said Mr Firat. "It is a violation of the rule on the separation of powers."
Hundreds of people, many of them women in headscarves, protested in several cities across Turkey on Friday to express their anger at the court's move.
The court said the government's move to overturn the ban violated the constitution's secular principles.
The ruling could foreshadow the outcome of a case in which the AK Party could be banned, correspondents say.
Turkey's chief prosecutor says the ruling AKP is "the focal point of anti-secular activities" and is seeking to have it disbanded.
Some 71 members of the party, including the prime minister and the president, could also be banned from belonging to a political party for five years.
The prosecution case cites the constitutional amendment allowing girls to wear headscarves to university as evidence that the AK Party - which has Islamist roots - has an anti-secular agenda.
The government argues that banning headscarves at colleges stops many Muslim girls being educated and says it is a matter of personal freedom.
The Turkish press agreed that the ruling upholding the headscarf ban had been Mr Erdogan's "greatest political defeat" since the AKP came to power in 2002.
Some within the AKP believe members will have to set up a new party only a year after it won a convincing poll victory, says the BBC's David O'Byrne in Istanbul.