The claim was made during a speech at an industry conference in London.
Mr Marchant said: "Personally, I believe that when it comes to the energy retail market, Ofgem and DECC do not have a clear vision.
"They have good intentions, but there is no clear vision with no clear measures of success."
Mr Marchant also warned that rushing into changes may give rise to more problems.
One example he cited was that forcing energy companies to have a smaller number of tariffs may actually reduce the number of customers who switch between suppliers.
He said: "DECC and Ofgem get forced into a corner and react in the way they know how, to create rules and regulations, often in tight timelines and in the political and media spotlight.
"Because there is no overarching vision, there is a serious risk of meandering around from one piecemeal intervention to another.
"We are in turmoil, and I fear because of a lack of vision it will get worse before it gets better."
In a light-hearted section of the talk, Mr Marchant compared energy competitors to safari animals, suggesting Centrica is like a lion which "struts around", while ScottishPower was associated with a rhino as it is "thick-skinned and impossible to describe and predict".