A man woken up by gardai searching his home was "confused" and "disorientated" when he obstructed a female officer at the top of the stairs.
Jason Farrell (26) was aggressive and gardai were forced to use pepper spray to subdue him.
Judge David McHugh fined Farrell €150.
The defendant, of Huntstown Avenue, Mulhuddart, admitted wilfully obstructing Garda Laura Caffrey at his home shortly after 1am on May 4 this year.
Sergeant Maria Callaghan told Blanchardstown District Court gardai went to the defendant's home after receiving a report a man had been stabbed. It later turned out to be false.
Sgt Callaghan said the owner answered the door and allowed gardai to search the premises.
Sgt Callaghan said Gda Caffrey met Farrell at the top of the stairs and she explained to him about the search.
She said Farrell immediately became aggressive and abusive toward her and tried to obstruct her from searching the rooms.
Sgt Callaghan said Farrell was told to desist in his behaviour, but he failed to do so and was arrested.
Sgt Callaghan said gardai were forced to use pepper spray in order to subdue the defendant.
The court heard Farrell has 20 previous convictions.
Defence solicitor Fiona Brennan said Farrell had been asleep and was disorientated and confused when he came out of his bedroom and saw gardai.
Ms Brennan accepted the defendant had "acted inappropriately", but said he had no idea why gardai were there.
She also said the call to gardai came from within the house, and officers searched it from top to bottom but there was no one who had been assaulted.