At the press conference of IIFA awards Thursday night, Salman was asked what message would he give about conservation of environment.
"Green firstly (save trees), (save) water, avoid plastic. Swatch Bharat- Fit Bharat. Don't use plastic and don't be plastic," the superstar told reporters.
Madhuri said parents should think about the kind of planet they want to leave behind for their children.
"I think we have to be responsible and each one of us has to take the responsibility and say that I am going to be an ideal citizen and I am going to do something for the environment.
"However small it is, like save water or don't use plastic, there are so many things you can do for the environment, and each one of us can do it in our own little ways," she said.
Katrina said that since climate change is not something that "we see directly every day", people forget how important it is to save the environment.
"I think the most easy thing to do in our lives to is stop single use of plastic, it will be of great help to the planet. I think PM Modi ji's initiative is incredible and that's something we all should support.
"It is as easy as that- don't drink water out of plastic bottles and try and carry another kind of container to hold your water," the actor added.
IIFA Awards nights will be held on September 18.
Prime Minister Modi, who is leading efforts to scrap single-use plastics by 2022, is likely to announce a ban on a few items on October 2, the birth anniversary of Mahatma Gandhi.
Modi, in his Independence Day speech, had urged people to avoid using plastic bags, and technicians and entrepreneurs to look at innovative ways to recycle plastic.