Tl;dr: no, it's not correct.
There isn't a perfect one-word translation for "suspenseful". You can use "emocionante" or "intrigante", although those are closer to "exciting" or "thrilling". The translation for "suspenseful" most searching engines offer is "de suspenso"1:
I cover my eyes during the most suspenseful parts of a movie = Durante los momentos de [más] suspenso, me tapo los ojos. – SpanishDict
This is going to be the single least suspenseful meeting of my day. = Esta será mi reunión de menos suspenso de este día – Reverso
An alternative is "con suspenso". "To be suspenseful" can be translated as "tener suspenso", which is probably the most common alternative, or "estar lleno/a de suspenso", which is more emphatic:
It was more suspenseful than I thought. = Tenía más suspenso de lo que pensé – Reverso
The movie was so suspenseful that it had me on the edge of my seat = La película estaba tan llena de suspenso [que] me tenía en ascuas. – SpanishDict
In any case, "suspenso" is a noun, not an adjective. Etymologically, "suspenso" is an adjective inasmuch as it is the participle of "suspender", along with "suspendido". As many other double participles, there was a time "suspenso" was used in passive contructions:
"Y al poco tiempo, por el mes de Agosto, año de 1587, vino por Presidente y Visitador general de esta Real Audiencia el Dr. Manuel de Barros San Millán, el cual le visitó y a los demás que lo habían sido, y en el discurso de su vistía fue suspenso y enviado a España."
Rodríguez Docampo, Diego (1650). Descripción y relación del estado eclesiástico del Obispado de San Francisco de Quito
Nowadays, most double participles have lost that property: the irregular one works as an adjective (which means it can't be used in compound verb tenses or passive constructions) and the regular one works as both an adjective and a participle. Two notable exceptions are "frito" and "impreso", which can be used as participles even though a regular participle exists (freído, imprimido).
Another characteristic of irregular participles is that they may also work as nouns. Some examples are "respuesta" (participle form of "responder"), "tinta" (participle form of "teñir"), "llanto" (participle form of "llorar"), or "producto" (participle form of "producir"). All of these work exclusively as nouns today, although that may not have always been the case:
"[El lenguaje] se halla en la propriedad [sic] de la luz o resplandor o lumbre, que es llamado el Verbo eterno, porque siempre depende el resplandor de la luz que le despide, y siempre está producto."
Pineda, Juan de (1589). Diálogos familiares de la agricultura cristiana
"Suspenso" shares both properties mentioned above: it is an adjective meaning suspended, both in the sense of "cancelled" and "hung"/"hanging"; and it is a noun meaning "suspense". If you say "La película fue suspenso", you're saying "the movie was suspense", which doesn't make any sense. If you say "La película fue suspensa", you're saying it was suspended, although most people would say "la película fue suspendida" in that case because irregular participles aren't used in passive constructions if there is a regular one available (see blocking).
The best way to say "the movie was suspenseful" is:
La película estuvo llena de suspenso.
Finally, "de suspenso" describes the thriller genre, so saying "película de suspenso" wouldn't mean a suspenseful movie but just a thriller. When describing a movie, novel, or any work that could potentially belong in the thriller genre, "lleno/a de suspenso" resolves the ambiguity.
1: "Suspenso" is commonly used throughout Latin America, while "suspense" (pronounced /sus.pen.se/) is preferred in Spain in the sense of "suspense". An exception is the expression "en suspenso" (pending, temporarily cancelled), used on both sides of the pond. The form "en suspense" is incorrect. [DPD]