The Turin giants recorded a 3-1 win on Tuesday to take a major step towards the final, but Dybala has stressed they are not there just yet.
"The scoreline looks good now but we must not underestimate Napoli," Dybala told the club's official website.
"They are sure to make it tough for us at their place in the return leg."
Juventus found themselves trailing 1-0 at half-time, but a strong performance after the break saw them emerge victorious in the end.
"It was a tricky game, especially in the opening 45 minutes," Dybala, who scored two of Juve's goals, added.
"We spoke together at half-time when we were a goal down then came back out and instantly put into practice what we had discussed in the dressing room..
"We changed attitude. We went out there with a different mindset and were more aggressive. Getting the first goal straight after the restart helped too."