"It was an interesting movie." Any specific rule that the word INTERESTING ends with ing. Can this word be used as a participle or a gerund phrase?
There is a verb "to interest". It is not often used as a participle or gerund, but it is possible:
The first stage in teaching maths is interesting your student in the subject.
However this is a garden path sentence. The use of the gerund is unusual and so the brain parses "interesting" as an adjective, then has to back up. I would rephrase as "getting your student interested".
Participle use is also possible
Flower arranging is interesting me at the moment.
Interesting her with the promise of large profits, the conman deceived the woman.
It is possible, but perhaps not a good idea.