European Union officials are calling on Turkey to halt its military action in Syria after Turkish forces shelled positions held by a U.S.-backed Kurdish militia over the weekend.

The EU's foreign policy chief, Federica Mogherini, said Monday that "only a few days ago, all of us including Turkey, sitting around the table decided steps to de-escalate and have a cessation of hostilities."

She said more fighting "is obviously not what we expect."

Dutch Foreign Minister Bert Koenders, whose country holds the EU's rotating presidency, said "we have the plan for a cessation of hostilities and I think everybody has to abide by that."

Syria's main Kurdish faction, the People's Protection Units, has been most effective in combating the Islamic State group, but Turkey appears uneasy over the group's recent gains.