It was recently reported that the Polish racing driver was working with the Brackley-based F1 team after being spotted heading to the factory from Heathrow airport by a rival team member.
The 27-year-old told Autosport.com: "I can say yes, I was there, but I cannot say how many times or how many laps I did, but there is this rumour to which I say, yes, I was in the Mercedes F1 simulator in the past.
"Maybe [I will drive there again], I don't know. But it's not that every time someone sees me at Heathrow airport I am going to Mercedes. I am also at Heathrow for different reasons, it doesn't always have to be a connection with that."
Kubica has not competed in F1 since 2010, having partially severed his forearm in a crash at a rally in Andorra.