Officers are appealing for witnesses after a member of the public called about the unknown woman in Rotherham on Thursday.
At 2.10pm, they said they had seen a woman being forced into a silver Volkswagen Golf by a man wearing a green tracksuit outside Millhouse Court.
Despite extensive enquiries, police have not been able to identify the man or woman involved, or ascertain the circumstances leading up to the incident.
Rotherham DCI Aneela Khalil-Khan said: “Our priority is to identify this woman and confirm that she is OK.
“We do sometimes receive reports of this nature and often it can be easily explained, however we need to ensure she is safe and well.
“If you are the woman involved, please come forward and let us know you’re OK.”
Anyone witnesses can contact 101, quoting incident 546 of 31 March.