Sterling, 19, is set to be deployed on the wing for England at the 2014 World Cup, for their Group D campaign against Costa Rica, Italy and Uruguay.
The Liverpool starlet has the hopes of a nation resting on his shoulders, after a brilliant Premier League campaign at Anfield.
Barnes, 50, who played at the 1986 and 1990 World Cups for England, said their fans should not overburden the teenager.
"I still don't want to put so much pressure on him now that he has shown so much quality in the last few months of the season," Barnes said.
The former Watford and Reds man Barnes conceded while he and Sterling both shared a birth nation - Jamaica - there was little else in common.
Barnes said Sterling has also proven himself to be a reliable performer, despite his youth.
"Maybe he is going to be inconsistent because he is young," he said.
"But in terms of what he did in the last few months of the season, he was probably the best player in England.
"Not the best English player; the best player in England, the best attacking player in England."
'David Beckham was desperate to play in my squad, but I didn't want to bring him along and waste the FA’s money: I had to pick the strongest players': Great Britain coach reflects on Becks snub as 'one of the toughest decisions' of his career
Manchester City report: Bruno Guimaraes and Pep Guardiola discussions revealed, as rumours swirl he could replace Rodri
