Short answer
First, move the bowl and any other human snacks out of reach. Pine nuts are high in fat and can cause stomach upset in cats. A few nuts likely won't cause serious harm, but watch for signs like vomiting, diarrhea, or a lack of appetite over the next day or two. Since cats are smaller and more sensitive to rich foods, it's wise to monitor them closely. If your cat ate a large handful or shows any concerning signs, a call to your vet for guidance is a good idea.
Pine nuts — Food safety facts
Feed with care · Cats · full breakdown on the linked food page
High in fat; in dogs they have been linked to a temporary taste disturbance and liver upset.
The full verdict, portion guidance and serving notes are collected on the Pine nuts food facts page.