Preston New Road in Little Plumpton was blocked in both directions earlier because of 'people in the road', police said.
Motorists were told to find alternative routes because of the obstruction, close to Cuadrilla's fracking site, at around 11.20am.
A spokesman for the force said the road was 'passable with caution' by noon, though he urged drivers to 'please be aware of people in the road'.
The site has seen on-going anti-fracking protests, which The Gazette yesterday revealed is costing £450,000 per month to police, and has led to a number of arrests.
In a statement, Lancashire Police told The Gazette: "A section of Preston New Road was blocked due to a number of protesters being in the road near to the entrance to the Cuadrilla site.
"It is now accessible but we are urging motorists to drive with caution."
A spokeswoman for the North West Ambulance Service (NWAS) said paramedics were called to the site at 11.18am, after a man in his 20s suffered a suspected leg injury.
He was taken to Blackpool Victoria Hospital for further treatment, the spokesman added, though she could not say how he was hurt.
One Facebook Live video, purportedly shot by a protester at the site today, claimed the man's ankle was injured after he caught it in fencing.
Police said no arrests had been made.