Former Arsenal skipper Henry has faced United on numerous occasions in England and says his side know what to expect from the Red Devils.
"They are a team in first place in their league and Cristiano Ronaldo is having an incredible season, so we know them pretty well. They won't be able to surprise us," he said.
The Frenchman denied he would be particularly motivated against one of his former club's biggest rivals and claimed this match will be very different to any Arsenal-Manchester United match.
"There is none of that (ill-feeling). An Arsenal-Manchester United match is another thing, but this is a big game and we are going to fight to be in the final," he said.