Semitecolos said the man tried to enter the concession stand through a window before using the crowbar to gain entry through a door, the television station reported.
The man stole cash from a donation jar and also took the cash register, also taking a package of hot dogs, WFTS reported. The cash box contained $250, the Times reported.
"He robbed the whole cash box because he couldn't get it open, and he took the kids' donations," Semitecolos told WTVT.
The man also stole three surveillance cameras and broke the lock on a gate covering a sliding glass window, the Times reported.
"It's disturbing. It's hurtful," Semitecolos told WFTS.
Derek Dormois, a high school senior who played baseball at the Little League complex and now helps younger players, said he was shocked by the robbery.
"It blows my mind, especially here in Dunedin. It's a nice, safe community. Growing up, we never really had that issue," Dormois told WTVT. "It's not just baseball. It's family. It's friends.
Police are still looking for the suspect.