Man sees sniper !
 

From a high building he sees a rifle emerging from a curtain and kills someone. It then 'sees' him and he then goes on the run from an unknown assailant! He meets a girl and they go to a hotel. A knock at the door says 'room service' ,she opens door(on the chain) and a knife tries to stab here but cant get her because of the chain. Think it might be Jimmy Stewart (not Rear Window) or someone very like him.

Re: Man sees sniper !
 

So this is an old movie?

Re: Man sees sniper !
 

7 days to condor?

Okki2, Are you sure you don't mean "Three Days Of The Condor" from 1975?

TooSoonTom, if it is a movie starring James Stewart then "The Man Who Knew Too Much" from 1956 has the bit about a sniper hiding behind a curtain ready to kill a foreign Prime Minister but only wounds him. The rest of your description doesn't fit though.