Honestly, Pamplona is not precisely the ultimate city to visit with children. There are no beaches and no significant fun zones in the area. Still, you can spend wonderful with the kids following the big part of the agenda that applies to adults too.
Show them the route of the Encierro and the monument with the bulls. Get them to taste pintxos. Take a walk around the park. Visit the Planetarium. Attend a football game if there are any tickets available. The game zones in the shopping malls are always an opportunity. Bellow you can find the best things to keep the kids entertained whilst your in Pamplona