The Romanian, who can play at left-back or in central defence, was linked with City during Roberto Mancini's time as manager at the Etihad Stadium.
The 26-year-old's agent Victor Becali claimed his client was "appreciated" by Mancini, but following the Italian's sacking in May he states there has been no contact from the former Premier League champions.
"Neither I nor Lazio know anything of Manchester City's interest in Radu," said Becali.
"I have a great relationship with Txiki Begiristain. If City were interested in the player they surely would have called me."
City left-back Aleksander Kolarov was a team-mate of Radu's at Lazio before signing for the Blues in July 2010.