The EU regulation 1989/654/EEC Annex 1 states this:
Room dimensions and air space in rooms — freedom of movement at the workstation
(15.1) Workrooms must have sufficient surface area, height and air space to allow workers to perform their work without risk to their
safety, health or well-being.
(15.2) The dimensions of the free unoccupied area at the workstation must be calculated to allow workers sufficient freedom of movement to
perform their work. If this is not possible for reasons specific to
the ►C1 workstation ◄, the worker must be provided with sufficient
freedom of movement near his workstation
So it's all very vague which allows independent countries (Or even companies) to be able to define what is considered sufficient freedom of movement to perform their work
The EU generally does this on purpose so to not enforce specificities, but allow each country to define it's own definition of the rule:
A regulation shall have general application. It shall be binding in
its entirety and directly applicable in all Member States.
So to answer your question, no the EU regulation does not define a minimum size for an office space. It just implies it should be suitable for the work being carried out in that space.