Cavanagh sustained a knee injury during his club Moy's county league match against Cookstown on Sunday.
"We feared possible ligament damage to Colm's knee but it seems it is just bruising," said Harte.
However an ankle injury will probably rule Tyrone defender Ronan McNabb out of the 16 July decider at Clones.
Attacker Darren McCurry is also a doubt for the clash with Down, and was unable to complete a club game on Sunday.
"Darren had been carrying a bit of a calf muscle injury, and had to be careful about contact," added manager Harte.
"When he had to go off it must have been giving him quite a bit of bother."
Skipper Sean Cavanagh missed his club's league game at the weekend, but Harte is confident he will be fit to lead the team out at St Tiernach's Park as Tyrone go for a second straight provincial title.
Tyrone boss Mickey Harte expects injured midfielder Colm Cavanagh will be fit for the Ulster Football Championship final against Down.