"There is a need for Turkey to respond to the call from the European Union side, as a candidate country, to respect the highest standards when it comes to democracy, rule of law, fundamental freedoms starting from freedom of expression and freedom of association," Mogherini said in remarks broadcast by the European Commission audiovisual services.
The EU-Turkey summit focusing on stemming migration flows into the bloc kicked off in Brussels earlier in the day.
"These are core values of the European Union, any candidate countries has to stick to these principles and values and work completely to promote them within its borders," Mogherini stressed.
On Friday, a Turkish court ordered the Feza Media Group, which includes opposition newspaper Zaman, Today’s Zaman daily and the Cihan news agency, to be placed under the management of government trustees.
Online and physical access to the news services and publications was subsequently cut after the government takeover.
The decision led to mass riots in the largest Turkish city of Istanbul. Turkish police used tear gas, water cannons and plastic bullets to disperse the protesters over the weekend.
European Parliament Martin Schulz pledged to address the press crackdown issue with Turkish Prime Minister Ahmet Davutoglu at the summit.
