He was pressured by the FBI to inform against his own friend.
This means that the FBI pressured him, AND he ACTUALLY DID inform against his own friend. Right?
Then, what do you say if you don't want to refer to the part of whether he did actually inform his own friend or not?
In another words, what do you say only
The FBI pressured him and said to him 'You'd better tell us about your friends.'
Starting with "He was pressured by the FBI..." without referring to whether he actually did so or not.