United manager Sir Alex Ferguson claimed the French defender should have been sent off at the weekend by referee Alan Wiley for kicking Nani from behind in response to the Portuguese midfielder indulging in some ball-juggling.
However the Football Association confirmed today that Wiley had looked at video footage of the incident.
An FA spokesman said: "Having viewed the footage, the referee was not satisfied that it showed evidence of violent conduct and therefore no further action will be taken."
For the FA to take action, Wiley would have had to have deemed the clash worthy of a red card for violent conduct.
The decision will be sure to infuriate Ferguson, who said after the 4-0 win by United: "I thought Gallas should have been sent off. The referee must have a look at that again.
"He kicked Nani from behind and the referee called both over because they sized each other up. He should have been red-carded."