Ms Creagh said her staff discovered the damage at the constituency office in Wakefield city centre this morning.
Poice confirmed they had been informed.
Ms Creagh said on Twitter: “Staff distressed to discover brick through office window in Wakefield this morning. No excuse for violence and intimidation in our democracy.”
A police spokeswoman said: “Police were called to an address on Cheapside in Wakefield at 12.50pm today following reports that a brick had been thrown through a window.
“The building was unoccupied at the time. Enquiries are ongoing to determine the circumstances surrounding the incident.”
“Anyone with information is asked to contact police via 101 quoting 725 of September 12.”