Secrecy surrounding the talks has fuelled fears that US corporations may erode Europe's consumer protections.
But the EU's top trade official denied any agenda to lower EU standards.
"I am simply not in the business of lowering standards," said EU Trade Commissioner Cecilia Malmstroem in her blog, after the Greenpeace leak was published.
TTIP's supporters say a deal would create many new business opportunities.
TTIP stands for Transatlantic Trade and Investment Partnership. It would harmonise regulations across a huge range of business sectors, providing a boost to exporters on both sides of the Atlantic.
The 13th TTIP negotiating round took place last week and the European Commission says it hopes to achieve a deal later this year. That could avoid any political risk posed by the US presidential election in November.
The EU's chief negotiator, Ignacio Garcia Bercero, said some of Greenpeace's points were "flatly wrong", and stressed that the leaked text "is not a reflection of the outcome of the negotiation".
Read more: TTIP trade talks: Greenpeace leak 'shows risks of EU-US deal' - BBC News