The office in the 2100-block of North Milwaukee Avenue had several glass windows and a glass door shattered.
The alderman said it happened around 12:45 a.m. He said two men dressed in black smashed the windows with a bat or a tool. Chicago police confirmed they were called to the scene by a witness.
La Spata, who is running for a second term against three challengers - Proco Joe Moreno, Sam Royko and Andy Schneider -- said nothing was taken from the office, and is wondering if the incident was politically motivated.
"It's disappointing. To me, it is a vestige of an old way of doing politics in Chicago that is dying slowly but dying for sure," he said.
La Spata said he has a surveillance camera at the office, but it was apparently not working at the time of the incident. He is hoping other cameras on the block captured something.
The office has now been boarded up, but there is still quite a bit of broken glass. No injuries were reported.
Andy Schneider condemned the incident, saying, "It's a reprehensible act. There is no absolutely no place for this sort of behavior in Chicago politics. Perhaps there used to be, but that time has passed. It shouldn't be this way anymore."
And Sam Royko released a statement, saying, "This type of behavior has no place in our community or politics."
ABC7 reached out to Proco Joe Moreno, but we have not yet heard back.