いたずらじゃなかったです
悪戯じゃなかったです
itazurajanakattadesu

Noun
Desu Copula
na-Adjective

The polite, past negative form of いたずら

1. It wasn't a prank.; It wasn't mischievous.

Past/Perfective
Negative
Polite
Casual Register
Usually Written in Kana