They asked for money from the vehicles between Aseergarh and Nimbola on the Indore-Icchapur highway in the district, police said.
A complaint against them was filed by a farmer, Prem Singh, who was carrying the bovine animals and they collected Rs 400 from him in the name of entry fee, Additional Superintendent of Police (ASP) Satyendra Singh Tomar said.
After conducting a probe in this regard, constables Rajesh Bamania, Mukesh Patidar, Dinesh Damor and Hameed were placed under suspension, he added.