Sources at the super high-end 1-Oak nightclub tell us LiLo was definitely inside the joint ... but didn't order a single drink ... and was not seen sipping on anything alcoholic.
Lohan was also spotted at the Simyone Lounge -- but Lindsay tells us, "I did not drink ... period. I do not drink ... period."
Lohan added, "I went to SL with my friend who owns it."