The government responded by saying it was "disappointed" with the Amnesty report, which had "significant shortcomings."
Amnesty's Middle East and North Africa deputy head Said Boumedouha said "four years on from the uprising, repression is widespread and rampant abuses by the security forces continues. Bahrain's authorities must prove that the promises of reform they have made are more than empty rhetoric.
A government statement said Amnesty "misreported" Manama's "respect of the rights to freedom of opinion and expression and to peaceful assembly" which are "protected by Bahrain’s constitution".
"The government continues to uphold them robustly. Yet as any other responsible government, the government of Bahrain will not tolerate violent attacks or incitement to violence committed under the guise of free speech and peaceful protest.
"It is the government's duty to protect citizens, residents, and visitors alike and the government makes no apology for doing so. Bahrain will respond to such attacks in accordance with its law and best international practices."
In its report, Amnesty said Bahraini authorities arbitrarily detain activists with excessive use of force.
The details testimonies of detainees -- some as young as 17 -- describing being beaten, tortured and threatened.
Signup to our newsletter and follow us on Facebook and Twitter!
One told Amnesty he had been struck with the claw of a hammer on several parts of the body.
Those held in pre-trial detention are also routinely tortured to extract confessions, the report said.
"As the world's eyes fall on Bahrain during the Grand Prix this weekend, few will realise that the international images the authorities have attempted to project of the country as a progressive reformist state committed to human rights masks a far more sinister truth," said Boumedouha.
Bahrain, home to the US Navy's Fifth Fleet, has been rocked by unrest since security forces crushed Shiite-led protests in 2011 demanding a constitutional monarchy and an elected prime minister.
The tiny Gulf state banned public demonstrations in 2013.
At least 89 people have been killed in clashes with security forces, while hundreds, most of them Shiite, have been arrested and put on trial, human rights groups say.
Shiite opposition leader Sheikh Ali Salman is behind bars for allegedly trying to overthrow the regime.
His arrest in December shortly after he was re-elected head of Bahrain's main opposition party Al-Wefaq has sparked near-daily protests in Shiite villages.