After their 2-2 draw at West Ham, O'Neill said: "We want to do our utmost to keep Gareth because he's so important to us and is back to his brilliant best.
"I will not be made to feel under pressure by other clubs because they want one of our players. We're going to talk it through with Gareth.
"I can't understand why Gareth would want to leave. He's only 27 and has been brilliant for us.
"He has been selected for England and has played regularly for them because of his exploits with Villa.
"In terms of him playing in the Champions League, we can guarantee him that within the next 23 years!"