Nope.
A pardon stops all punishment from the judicial system. You don't have to plead guilty and criminal proceedings stop. A pardon further undoes any legal handicap (for example, you can own firearms again).
That said, if you accept a pardon you can't plead the fifth when it comes to details related to the crime you've committed.
There's also a commutation, which is weaker than a pardon. Instead of having the crime fully forgiven you are simply let out of jail with the understanding you committed the crime and must face follow up consequences (like not being able to own firearms).
Finally, there are also conditional pardons. Those are ones where the president could impose a "you must plead guilty" style rule before the pardon can be applied. He could also apply a rule that says "you must perform 10 jumping jacks".
Pardon powers are some of the most broad we have in the US.
About the only limitation is you can't pardon for future crimes.