Google is placing a restriction on my website , i dont know why and how to remove this restriction.

Can you describe the situation a bit? something like what the message said.

get the reason directly from the horse's (google's) mouth. Always works like a charm

Possible reasons:
1) You are employing black hat SEO techniques
2) You are running scripts that google deems flaggable

Again, email google and hopefully they will answer your email soonest. good luck!

@ post
Ask Google!!
Use their Support forum.

Alternative
Tell Google to go to hell like john chow did for 3 years buton a second thought dont do that- you are not john chow!! find out the reason, et rid of it, then file your appeal.

it happened once to a site that was infected with virus. i followed google and got to register the site somewhere on google webmaster tools. and it
told me to resolve the problem and then they rechecked it and resolved it a few days later. but i removed the virus first.

*dhtml:

it happened once to a site that was infected with virus. i followed google and got to register the site somewhere on google webmaster tools. and it
told me to resolve the problem and then they rechecked it and resolved it a few days later. but i removed the virus first.

I have similar case with one of my sites. They wrote to me about the incident, I just remove the malware and notified them. That is all.

Exactly. once you remove the source of the problem and request for their review, they will remove it and that will be all.