A truck broke through the gates of the Russian embassy in Dublin, believed to be protesting the Russian attack on Ukraine.
The driver was arrested, Irish broadcaster RTÉ reported on Monday.
The man reversed the vehicle against the entrance to the site in the Irish capital, got out and distributed photos of alleged war victims.
Police confirmed they were investigating an incident of property damage.
The Russian embassy condemned the incident as a "criminal act directed against a peaceful diplomatic mission."
The act took place under the eyes of police officers who were idly watching.
The embassy has urged the Irish authorities to take "comprehensive measures" to ensure the safety of embassy staff and says it is in contact with the Foreign Office.
Russian embassy speaks of "barbaric acts"
“The incident is of great concern.
We believe that no sane person can support such senseless and barbaric acts.
Police said they did not comment on statements or remarks made by third parties.
Protests against the Russian war of aggression have been taking place in front of the embassy for days.
Ambassador Yuri Filatov had previously spoken of death threats against diplomats and their family members.
Russian children have been discriminated against in Irish schools.
svs/dpa