The Ligue 1 club have tied down the forward to a further two-year contract and reached an agreement for the midfielder to reduce his salary
Goal reported that the France international striker was high on the wanted list of Newcastle during the summer transfer window but no deal could be agreed before Monday's deadline.
And Aulas has now stated that Lacazette has signed a new deal, reportedly through to 2018, while also revealing that midfielder Yoann Gourcuff - who has struggled for form and fitness since joining in 2010 - has agreed to play this season on reduced terms.
"Yoann Gourcuff has agreed to reduce his salary for the season and we have extended the contract of Alexandre Lacazette by two years," Aulas said at a news conference.
Lacazette has started the new season well with three goals in four Ligue 1 matches.
However, the team have not replicated that form and have won once and lost three league games.