"Still not feeling well so won't be making it to #TirrenoAdriatico2015 Really disappointed but health comes first! Time for some R&R..." Froome wrote.
Shortly afterwards, a statement was published on the Team Sky website, explaining that Froome has a chest infection.
"This is obviously frustrating after the good start that I've had to the season, but it's a minor setback. I've been ill for a few days now and unfortunately I couldn't shake it off in time for the race," Froome said. "After speaking with the doctors we decided as a precaution that it would be best to take a few days off the bike to recover fully."
It marks the second successive year that Froome has ruled himself out of Tirreno-Adriatico shortly before the start. Twelve months ago, he also opted not to race, citing a back problem.
The next race on Froome's programme is due to be the Volta a Catalunya, which gets underway on March 23, and ought to see him line up against Contador for the second time this year. Froome beat the Spaniard into second place overall at the Vuelta a Andalucia last month.
"We're only at the start of the season and I should be fine to race the Volta a Catalunya later this month," Froome said.
Froome was the lone active rider named as having provided information to the Cycling Independent Reform Commission, which published the report of its year-long inquiry early on Monday morning.
"I sat down with CIRC after the end of the season last year and spent a good few hours with them, just talking about the state of the sport and how, from a rider's point of view, they can try to improve on things," Froome told The Daily Mail last week.