Ex-NBA Ref Tim Donaghy Arrested for Assault, Allegedly Threatened Man with Hammer

If you found out someone you loved was doing drugs -- and you knew you could stop it -- would you grab a hammer and try to rescue that person???

That's the story behind the arrest of Tim Donaghy -- the ex-NBA ref who went to prison for betting on NBA games that he officiated.

Donaghy was arrested in Florida on Tuesday for allegedly threatening a man with a hammer ... but he told police the only reason he was even in that situation was to save his daughter.

According to the police report, Tim believed his daughter was doing drugs with a friend at a nearby home -- so he grabbed a hammer and went to get her.

While Tim was arguing with his daughter outside the home, he was confronted by another man -- the father of his daughter's friend.

The man claims Tim brandished the hammer and threatened to use it, if he came any closer.

Police were called and Tim was arrested for aggravated assault.

Donaghy's attorney tells TMZ Sports his client did NOT assault anyone -- and didn't threaten anyone -- he only had the hammer for protection. Tim insists he was just trying to be a good dad.