The stone plaque was found broken by a mason yesterday, Senior Police Superintendent Rakesh Singh said, adding a case has been registered.
The Mathura MP was scheduled to arrive in the city today to dedicate to the people the beautified intersection.
Meanwhile, the city residents have alleged that the Opposition as well as the councillors, who were not happy with the inauguration programme, might be behind the incident.
Singh said CCTV footage of nearby shops is being checked to ascertain whether it was an accident or the result of someone's mischief.
Chairman of the local municipality Manish Gupta said the plaque contained apart from Hema Malini, the names of Councillor Umesh Sharma and some others.