Weird how cats love flowers, with mine (I'm also in Asia), no flower is safe, ever.
I think they need a steady supply of catgrass/wheatgrass. Get a heavy planter box, an oblong one, put it in an area where there is a lot of sun, and grow them some catgrass. Put stones at the bottom of it so it's heavy and they cannot topple it.
Mine also used to attack the few houseplants I had until I did that, and now they know there is a plant box just for them, and basically leave the other plants alone.
Don't punish them, this is natural behaviour, so use positive enforcement, like praising them when they eat the plants you give them.
Flowers are a different story, I am afraid - I have learnt to put mine out of reach, which is sad since that means in places you can't see them properly. It's OK with plants not toxic to cats, but my favourites are all toxic to cats so there we go. Remember to always check, and only keep safe plants in the home.