They say that they were patrolling areas of frozen water after receiving reports of people walking on the lake at Stratford Park.
A picture of a teenage boy walking on the lake was shared on Facebook yesterday, Saturday.
Officers are reminding residents not to walk on the lakes, ponds, canals and reservoirs under any circumstances.
This warning comes as two brothers were among four boys who died after being pulled from an ice-covered lake in Kingshurst, Solihull, near Birmingham.
Siblings Samuel Butler, six, and eight-year-old Finlay Butler, eight, died along with their cousin Thomas Stewart, 11, and Jack Johnson, 10, West Midlands Police said.