Hi Jacek,

It's hard to tell without seeing the flowers under magnification. However, I can definitively say that it is not a member of the Lamiaceae. All Lamiaceae members have opposite leaves, while this specimen's leaves alternate. If you can post a magnified image of the flowers I might be able to offer better help. Also, the Facebook group, Planet Plant ID, has myriad botanical experts who are often able to offer correct identification within a few hours. 

Good luck!

https://www.facebook.com/groups/planetplantid/

You are right about the family, thank you. Here are the flowers:

It is genus Parietaria (Urticaceae). There are three species in Croatia (see https://hirc.botanic.hr/fcd/ShowResults.aspx?hash=1317113734 ).

I believe this is Parietaria judaica.

Michal,

Thank you very much for the identification and for posting this web link! Best regards,

Jacek

Parietaria officinalis subsp. judaica (L.) Bég.

Now it's (Parietaria officinalis subsp. judaica (L.) Bég.) synonym to

Parietaria judaica L. ; According to The Plant List.

With best regards.

Parietaria judaica L.

Parietaria judaica L.