Robinho moved to Eastlands from Real Madrid in a £32.5million transfer in the summer of 2008 but his form for City has been patchy and he was taken off during the 2-0 defeat at Everton earlier this month after coming on as a substitute for the injured Roque Santa Cruz in the first half.
He was left out of the team for the midweek Carling Cup win against Manchester United but was picked in the starting eleven by City manager Roberto Mancini for the FA Cup fourth round clash at Scunthorpe United.
"What's important is to be happy," Robinho told Brazilian radio station Radio Bandeirantes.
"Money is not everything.
"First thing is that I am going through a bad period. Here, Mancini said that I would play one game and another no. I didn't accept that and told him so. It's a World Cup year.
"The directors all agree that it's better to send me out on loan. It would be exceptional to return to Santos.
"Playing for Santos would help me in my path to the World Cup. It is my home, I know everyone."