Two men are thought to have been posing as fishmongers while they looked for dogs to steal in Berkhamsted.
The suspected crooks were visiting businesses in Castle Street on Wednesday just before 12.30pm.
Police were called in by a member of the public concerned about their motives.
Herts Police spokesman Sarah Spence said: “It was thought they may have been trying to steal dogs.
“No offences had occurred.”
Anyone who sees suspicious activity can contact police via the non-emergency number 101, if a crime is ongoing dial 999.