Fetch as Google canceled your fetch because too many consecutive requests were made to the server for different URLs.
Is there any solution for this? How can I fetch my URL?
For general information on the rate limiting...
Google has specific limits on the number of fetches and URL submissions you can do which last time I saw where 500 fetches and 10 URL + linked pages submissions per week. If you go over this limit then you will be presented with the rate limiting error.
With regards to your specific error this does not appear to be rate limiting per-sey but rather a Google restriction on how many consecutive requests you can make to different URL's in a relatively small number of time. The important thing to note is that the fetch as Google is not designed to provide a gateway to load every single new page you make into Google rather it is designed to see how a page will look to Google and based on this model Google does expect some time between fetches.
Your comment appears to contradict your original question as it states that the error was a "Temporary Unreachable" error which is not a Google application error but rather a HTTP error which could indicate a temporary issue with the server you where connected to when you made the request in which case simply waiting and trying again after a few minutes should resolve it, especially with a platform as large as Google's.
Hopefully one of these points covers what the underlying issue was.