The report by the European Union Office to Hong Kong and Macau, dated October 8, detailed the contents of an hour-long meeting between Lam and the head of the EU office, Carmen Cano, the South China Morning Post reported on Tuesday.
Lam reportedly stated there was nothing to be gained by opening a discussion on something that could not be delivered at present. Universal suffrage is one of five core demands of anti-government protesters.
The Chief Executive said she had every intention of ensuring the district council elections, scheduled for November 24, would proceed as planned. But she noted it was "up to protesters", the report said.
In the meeting, which was described as "frank and candid", Lam played down her policy address, expected to be delivered on Wednesday, "with the crisis taking its toll on preparations".
According to the report, the Hong Kong leader considered that answering to the protesters' demands would be pointless at this stage and that she said "you can't negotiate with the mob", pointing to recent episodes of vandalism and illegal roadblocks.
Hong Kong has been embroiled since June in increasingly violent anti-government protests, sparked by a now-withdrawn extradition bill.
The mass protests evolved into a wider anti-government movement, with four other demands on the table, including calls for an independent commission to investigate police's use of force and universal suffrage for both the Legislative Council and Chief Executive.
Lam has so far refused to meet such concessions.
On Monday, thousands joined a peaceful rally calling on the US to pass the Hong Kong Human Rights and Democracy Act, which could pave the way for diplomatic action and economic sanctions against the city's government.
( With inputs from IANS )