According to Bo Smolka of PressBox, Harbaugh added that Flacco is in "good shape" and said they are currently awaiting the doctors to clear him for practice.
Flacco has missed all of training camp and the preseason due to a back injury.
On Monday, Harbaugh made it clear he had no concerns about Flacco's availability for Week 1 of the regular season against the Cincinnati Bengals, per Ryan Mink of the Ravens' official website: "He'll be back for the Bengals game and he'll be ready to play. I promise you that."
During Flacco's absence, Ryan Mallett has filled in as Baltimore's starter with Josh Woodrum and Thad Lewis also receiving work.
The 32-year-old Flacco is coming off an inconsistent season that saw him complete a career-high 64.9 percent of passes for 4,317 yards, but those records were somewhat offset by just 20 passing touchdowns and 15 interceptions.
After a career year in 2014, during which he threw 27 touchdowns, Flacco missed six games in 2015 due to a knee injury, marking the first time he had missed playing time since entering the league.
While Baltimore has missed the playoffs in each of the past two seasons, Flacco has led the Ravens to the postseason on six occasions, including the 2012 campaign when he turned in a dominant playoff performance en route to winning the Super Bowl.
Flacco has struggled to return to that level of play, but his health is key to Baltimore's playoff chances in 2017 since it doesn't have another proven quarterback on the roster.