Kasey Kahl's arrest the other night allegedly came after he smashed a woman in the face at a nightclub. No, it was not Vienna Girardi ... but we wondered too.

The former Bachelorette and Bachelor Pad star was arrested early Sunday a.m. for drunk and disorderly conduct at Club Habano's nightclub in Fresno, Calif.

According to the police report, Kahl was accused of attacking a man named Richard Chaney outside the club ... then smashing Chaney's girlfriend in the face.

Cops say Renee Idsinga told them she and Cheney were leaving the club when a "very intoxicated" Kahl  began "talking s**t" and that she tried to break it up.

Chaney told cops Kahl had been running his mouth about having banged one of Renee's friends. No, he's not talking about Vienna Girardi there either, people.

Idsinga says her BF told Kahl to "stop being a d**k and stop talking to her" and that's when Kahl started striking Chaney several times in the face and head."

Idsinga told cops Kahl struck her in the face in the melee, causing her nose to bleed. She also admitted she scratched Kahl's neck in an effort to break it up.

Kahl admitted that he had "a lot" to drink but insisted he DID NOT instigate the fight. Instead, Kahl claimed, "It was self defense." He was arrested regardless.

The arresting officer noted, "Kahl made it a point to tell me that he was a celebrity on several shows including The Bachelor and Celebrity Couples Retreat.'"

Not true in either case, but point taken.