Rooney has been out of sorts in a poor England side for the first couple of games in the campaign, only managing to draw with USA and Algeria.
But Sir Alex has been in touch with Rooney and advised his star player to relax.
Speaking to The Sun, Ferguson said: "Sometimes the expectation can be debilitating.
"I had that feeling. I spoke to Wayne Rooney and just said, 'relax and enjoy it.'
"I just sensed there was a tension in and around the camp from what I was hearing.
"I didn't watch the Algeria game, I was out with friends, but I just get a feeling that the expectation is affecting the England team."