Her comments come amid reports many teams on the grid, like Sauber and even the title-charging Lotus, are struggling to survive.
"Our finances are open for everyone to see," Williams, referring to the Grove team's listing on the Frankfurt stock exchange, is quoted by Brazil's Totalrace.
"We have a healthy budget and have done a good job on the business side to ensure that we are in a competitive situation as possible for next year," she insisted.
The daughter of team founder and boss Sir Frank Williams, however, said the fact Williams is in a healthy situation does not mean F1 should not do more to level the playing field.
"Williams has always embraced controls in spending," said Williams, "since they began to be implemented in 2009.
"It is very important for the sport.
"We are an independent team and so we can't afford to see costs increase when there is already such discrepancy in terms of (team) budgets.
"We must ensure that we can all compete more equally," she added.