Barnier took to Twitter on Monday to clarify the remarks, which were widely reported in British media and provoked an angry response.
The BBC reported Michel Barnier saying at a conference in Italy on Saturday that the consequences of leaving the EU had not been explained to the British people and Brexit would be an "educational process" for them.
Barnier took to Twitter on Monday to clarify the remarks, which were widely reported in British media and provoked an angry response from some eurosceptic British MPs.
"I said: #Brexit = occasion to explain single market benefits in all countries, incl my own. We do not want to "educate" or "teach lessons"," Barnier tweeted.
The row underlines the tense nature of the talks over Britain's exit from the European Union, the third round of which ended last week with Barnier warning that no "decisive progress" had been made.
The BBC had quoted Barnier as saying on Saturday: "There are extremely serious consequences of leaving the single market and it hasn't been explained to the British people. We intend to teach people… what leaving the single market means."
EU officials refused to comment on Barnier's comments on Monday, saying he was not speaking at a public event, but they drew criticism from some in London.
John Redwood, a lawmaker from Prime Minister Theresa May's ruling Conservative Party, told the Guardian that Barnier's "disobliging language" showed the EU was still in denial about Britain's decision to quit the bloc.
"I think it's very sad that the EU does not appear to be listening to the British people since the Brexit vote," the paper quoted him as saying.
The two sides clashed last week over the divorce bill, which the bloc has put at 100 billion euros ($118 billion) -- a figure Britain rejects.
Barnier demanded last Monday that London start "negotiating seriously" as a March 2019 deadline looms, with talks stalling over what comes first -- the divorce settlement or Britain's future relationship with the bloc.
But Britain's Brexit minister David Davis hit back on Sunday, insisting that Britain would not be pressured into accepting unfavourable terms.
EU leaders will review the talks in October to see how far they have got and whether it is possible to then take up London's demand for negotiations on a free trade deal but there is growing speculation the issue will be put back to December.