Yap Jin Keang, 37, made the plea after the charge was read out before judge M Kunasundary.
He was charged with inserting his finger into the vagina of a 26-year-old graphic designer in a car at a car park near Menara Felda, Jalan Persiaran KLCC, here, at 3.15pm on May 14.
The charge, under Section 377CA of the Penal Code, provides an imprisonment of up to 30 years and whipping, upon conviction.
Deputy public prosecutor Liyana Zawani Mohd Radzi did not offer bail as Yap had other cases.
Following this, the court refused him bail and set July 12 for mention.