According to The Telegraph the PM's office commissioned its own legal advice on the Agency Workers Directive, which concluded the impact of the new laws could be moderated.
The directive, to be introduced under EU law, will give temporary agency workers the same rights as full-time workers to pay, holiday and maternity leave after 12 weeks of employment.
But reports suggest Cameron is planning to strip down the laws for UK employers.
A spokesman from the Department of Business Innovation and Skills, said: "Ministers discussed these European regulations on a number of occasions with both the CBI and the TUC, seeking agreement on changes that we considered would have been to the benefit of both employers and agency workers. Unfortunately it was not possible to find a way forward that would be acceptable to both parties. This outcome was clearly disappointing.
"However, the Government took the view that the absolute priority must be to not to take any steps that could put at risk the 12-week qualifying period (which was agreed between the TUC and CBI in 2008) and so announced last year we would not be proceeding with any amendment of the Regulations.
"We continue to work closely with businesses and the recruitment industry to help them prepare for the changes and have recently published guidance that will help them fully understand their legal obligations as of October."
But Kevin Green, chief executive of the Recruitment and Employment Confederation (REC), added: "The REC has consistently highlighted some of the complexities within the Agency Work Regulations and we welcome the fact the Prime Minister is reportedly taking a direct interest in their impact.
"If the Government was to go head to head with the EU in simply refusing to introduce the new laws, there would be legitimate questions as to why this option was not pursued before as agencies have already invested substantial time and money in preparing for implementation on 1 October.
"In most sectors, the impact will be limited and recruiters are already working with their clients to make new equal treatment measures work. However, any measures to streamline the way that the regulations are applied would of course be welcomed.
"One realistic way forward would be for the Government to agree on an early 'one-year' review of the Regulations. This is something the REC as called for in recent discussions with Ministers. "We will keep REC members updated of any developments resulting from today's reports."