Is it a good idea to submit paper which is shorter than conference's page limit

I have seen papers rejected because it was shorter than the maximum allowed pages. But this was not the only reason for rejection; rather it was supporting that the paper didn't have enough contribution/content. If you don't want to give the reviewers any excuses to reject, then you might want to fill up the pages, but I think that's silly.

The answer would depend on the field and the page limit. If the page limit is 4, you probably want to fill all 4 pages, because 4 pages is usually not enough. But if the page limit is 12 pages, I see no problem for accepting a high-quality 11-page paper.

First I should mention that good conferences and journals logically do not pay much attention the the amount of pages of the papers. The quality of the paper and subject of it besides to the discussions and how much the topic is new seems to be more important than the quantity of the papers.

Check the conference's website to see if they policies on this issue or not. You may also ask your question from their office by email or phone.

The problem is my paper is 1 page shorter than the conference's page limit.

It is unclear that their page limit is a maximum number of pages or is a minimum number of pages. In the first case, I have seen some conferences which had a maximum limit of eight pages but some papers were accepted which were organized in nine pages. If there is a maximum limitation, then you have no problem as you are not passing the limit on maximum number of pages, your paper is in the safe side.

But if they "accept papers with no less than a number of pages", you should check this with the conference management. But still I think that there is no problem with shorter papers, specially your case which is inly one page.

By the way, you should also talk to the co-authors of your paper as they may have suggestion on your paper and may help you to extend your academic paper.