Gronkowski recently took part in full-pad practice for the first time since undergoing a number of surgeries on his arm and one on his back during the off-season.
The 24-year-old is a major doubt for Sunday's season opener against the Buffalo Bills, while next Thursday's match against the New York Jets may also come too soon for him.
However, Belichick refused to confirm whether or not Gronkowski would be available for those two games, stressing that they evaluate every player on a day-to-day basis.
"We evaluate each player day to day. We look at his situation the next day, and if he's improved and able to move ahead, then we move him ahead," Belichick told reporters.
"If not, then we keep him where he is, or sometimes there is a step back a little bit, and then you move ahead. It just depends on each individual player, his situation, what his progress is."
Belichick did, however, confirm that Gronkowski was moving forward in his recovery.