Speaking on a conference call to various national media outlets, Jackson mostly refused to speak about his departure from the Philadelphia Eagles, instead looking to focus on his future in Washington.
The 27-year-old said: "Robert Griffin has done a great job of embracing me, and calling me soon as I was a free agent. He said he would aim to do his best to get me here. I think they respect him enough out here to listen to him. He had a big part of me signing.
"Before I even got here, he came to my house out in California and said he needed me.
"DeAngelo Hall also stepped up to the plate and called me and just said, 'Look bro, I know I've been playing against you for a long time but this is a situation where I think if you came in here, I think you could help us out a lot.' So they have been very welcoming."
Jackson's deal with the Redskins is a four-year, $32m (£19.2m) contract.