Security measures have been strengthened further following an anonymous fax message received by police saying that bombs had been planted at 40 places in the city, police said on Tuesday.
Police issued a high alert in the night after receiving the fax on Monday evening and combed all parts but did not find any explosives, police said.
The fax, in English, was traced to a shop in the busy Ganesh Peth area of the city, they said.
The fax message dared the police to "stop us if you can".
Police stepped up vigil at all sensitive places and installations and also sent SMSes to citizens appealing to them to ignore rumours.
Although no untoward incident was reported, the city remained in the grip of tension with the Mumbai terror attacks still haunting the state and the country.
Pune, a satellite city of Mumbai, has, of late emerged as a centre of suspected terrorist activity in various forms.