Officers received a 999 call at around 1.20am on Tuesday after an attempted carjacking in Norman Road, in Smethwick.
A spokesman for West Midlands Police said: "It is understood a woman ran into the street to stop the car, banged on windows and tried to open the doors.
"It’s believed another car tried blocking in the target vehicle.
"The victim managed to drive off and was not hurt."
Anyone with information can call West Midlands Police on 101.
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org