All outdoor drinking and dining areas in Melbourne's CBD could be made smoke-free, if a proposal by the Lord Mayor is approved by the Melbourne City Council.

Quit Victoria said the move would make Melbourne the last Australian capital to introduce the ban, despite broad public support.

Director Sarah White said in areas where the ban was already in place, trade at cafes either improved or remained the same.

"If you speak to families, they don't want to take their children to sit outside at outdoor cafes, and the children will be subject to smoke drifting over from the next tables, so I think it would be a huge benefit for our culture," Ms White said.

"Victoria's been leading tobacco control measures internationally but for this measure we're falling very far behind, and it's looking like Victoria would be the last state in Australia to ban smoking in outdoor drinking and dining areas."

Lord Mayor Robert Doyle told 3AW it was time to have a discussion about stricter smoking measures.

"I reckon most smokers these days, if they're in an area outside dining they won't sit there and smoke, they'll go and smoke somewhere else," he said.

"I don't think it'd be a great imposition.

"Maybe that's the next step in ensuring we allow smokers to smoke but we make sure that when people are eating and enjoying themselves they are not interrupted by cigarette smoke."

Premier Daniel Andrews told Gold FM the proposal was worth considering.

"I can tell you as somebody with three young kids if we go out for breakfast we can't really sit outside," he said.

"One of our kids, our youngest kid Joseph, has asthma, so the outside area becomes the default smoking area and therefore a whole lot of families can't enjoy that.

"I think the time's come to have a proper debate about that and I think that's what the Lord Mayor is talking about."