Formula One's governing body is in discussion with the sport's 11 teams over the introduction of a budget cap.
FIA chief Mosley has long campaigned for a budget cap in F1
FIA president Max Mosley is keen on the measure in order to reduce F1's vast costs and level the playing field.
"We hope to produce a rule by June but we may run into problems that we haven't foreseen," said Mosley.
"We mustn't do it too dramatically, that's very much the topic discussed. You've got to pitch it on the high side to begin with and then bring it down."
An engineer is somebody who can do for one dollar what any idiot can do for 100 dollars
Mosley feels that the introduction of a budget cap would reward those who spent their money intelligently - and thus create a more even F1 competition.
"An engineer is somebody who can do for one dollar what any idiot can do for US$100," he said.
"That's very much the spirit of the thing."
At the meeting with F1 representatives in Paris, Mosley also proposed that teams should fund a dedicated group of forensic accountants to police any spending restrictions.
He suggested each team might contribute 2m euros to pay for a task force of about 30 financial experts who could inspect accounts and ensure the rules were being respected.
"If you are going, let's say, from (a budget of) 200m euros down to 100m, then even if you spent 2m euros a team you are still saving 98m," he said.
"For that kind of money, you can really check.
"The experience with McLaren and Ferrari taught us that if you deploy the resources and you get sufficient expertise, you can find almost anything.
"And the chances of somebody being able to do work that we couldn't find traces of start to be very small."
Mosley was referring to the spying controversy McLaren and Ferrari were embroiled in last year, with the FIA sending experts into the Mercedes-powered team's Woking factory to investigate their computer systems.
McLaren were subsequently fined $100m and stripped of all their constructors' points for the season.
The FIA has warned that failure to agree limits on expenditure would lead to more draconian measures, including severe restrictions on the use of wind tunnels.
But Mosley said that the teams were broadly in favour of a cap as a means of cutting costs.
Thursday's meeting was to discuss 'generalities' before going into more detail at a later date.