The goalkeeper was included in Steve McClaren's squad for Wednesday's friendly against Germany, returning to the international scene for the first time since the 2006 World Cup.
Pompey already have a long injury list and Redknapp does not want James to add to his woes by picking up an injury while with England.
"You speak to all the managers about England and they are the same. Liverpool, Chelsea and all the others would all rather there wasn't a game this week because you need your best players," Redknapp said.
"You're sitting there hoping they don't get injuries. You can't stop someone playing for England though. It's the greatest honour in the world if you're English. What more could you ask for?
"Jamo is probably as pleased now as when he was when he first got in the England team all those years ago. He's delighted. I wouldn't dare try to stop him."