"Eddie and Dave haven't stopped since day one of the season and both are carrying niggling injuries. They both need a break but because of the way the fixtures have been crammed together they haven't had a chance," said Blackwell in the Yorkshire Evening Post.
Lewis has played a major role in helping the USA to next summer's World Cup finals in Germany, and his American team-mates are due to take on Scotland in a friendly next weekend while Northern Ireland play Spain at Windsor Park.
"I'm sure Eddie will be of better use to the US at next summer's World Cup if he is fresh and not run down," added Blackwell. "He's played nearly 30 games already this season and we're only just in November.
"David just needs a rest. It's a glamorous game against Spain, but it's still a friendly, and I'd like him to have a rest if at all possible. It's like trying to squeeze juice out of an orange when there's none left. Rest is just as important as hard work."
Lewis is not expected to travel to France for the Whites friendly match with Rodez next Tuesday but Healy could be included in the travelling party, but is unlikely to feature.
Blackwell will finalise his squad for the trip today and he concluded: "There's a lot of lads that haven't had a game and there's a few young players who will benefit from the experience as well."