Radu was linked with City last week.
"There is no £12m Manchester City offer," Victor Becali told Radiosei.
"I also read these stories of a proposal for Stefan, but I can comfortably deny all of it. City have not requested Radu and the lad is very happy in Rome.
"If something like this were to happen, clearly the importance of the club in question would force Lazio to evaluate their options.
"It would be down to Lazio, but as things stand it's all idle chatter."