Protests have been held at the Preston New Road site in Lancashire since work began in January and one group has now promised "escalated action".
The local chamber of commerce said the tactics used by protesters were like those of "animal rights extremists".
Lancashire Police said it provides an "effective and proportionate" response, while facilitating peaceful protest.
Fifty-nine people were arrested at the site between 27 January and 17 March, with 47 of those being charged, police said.
Campaign group Reclaim The Power - which supports action already taken, including "slow walking, roadside protests and lock-ons" - has announced two weeks of "escalated action" to disrupt companies.
North and Western Lancashire Chamber of Commerce (NWLCC), which coordinated a letter to MPs and councillors about the protests, said businesses had endured "weeks of harassment and intimidation", with a St Annes concrete supplier withdrawing after it was "blockaded by an intimidating group of activists wearing hoods and masks".
NWLCC chief executive Babs Murphy said over 800 businesses wanted to supply the site and "deserve the chance [to] without fearing that they will be targeted".
The letter's signatories include East Lancashire Chamber of Commerce, the Civil Engineering Contractors Association and the GMB union.
Reclaim The Power said the letter was "yet another attempt by pro-fracking groups to falsely attack people who oppose them, and to distract from the fact that the industry doesn't have public backing".
Lancashire Police said the force was trying to "ensure a balance between the rights of people to lawfully protest [and] the rights of the wider public, including local businesses, to go about their lawful activities".
The government approved energy firm Cuadrilla's plans to extract shale gas at the site at Little Plumpton in October 2016.
Police need to "take a firm line" on anti-fracking protesters who target businesses, company bosses have said.