It said banning the visible wearing of any political, philosophical or religious sign in the workplace does not constitute direct discrimination.
The test case regarded the wearing of a Muslim veil in Belgium.
Speaking during Prime Minister's Questions, Theresa May was unconvinced by the ruling.
"It's the right of all women to choose how they dress and we don't intend to legislate on this issue," she said. "There will be times where it's right for a veil to be asked to be removed such as border security or perhaps in courts.
"Individual institutions can make their own policies but it is not for government to tell women what they can or cannot wear and we want to continue that strong tradition of freedom of expression."
The Church of England claimed the ruling was "troubling" but the Christian Legal Centre said it wasn't worried by it.
Chief Executive Andrea Williams said: "Yesterday's ruling in Luxembourg has not changed the law in the United Kingdom or anywhere else in the European Union.
"The Eweida ruling is still the law of the land and the Christian Legal Centre is here to defend anyone who is told by their employer that they are not permitted to wear their cross at work."
Nadia Eweida was the British Airways employee who fought for the right to wear a cross on her uniform.
The European Court of Human Rights ruled that BA did not reach a fair balance between Eweida's religious beliefs and the company's desire to have a particular corporate image.