World number 102 Andreeva was handed a point penalty after her racket flew out of her hand at 5-2 in the decider, giving match point to Keys in Monday's clash. She had already got a warning in the second set for throwing her racket.
An emotional Andreeva argued with umpire Louise Azemar Engzell to no avail, saying she had slipped on the grass and had not thrown her racket intentionally, before refusing to shake hands with her at the end of the match.
"The first warning I got, I think I deserved it... I was a bit frustrated. So that's why I threw the racket," qualifier Andreeva told reporters.
"Here I cannot say anything, she was right to give me a warning. I didn't complain or talk to her about it...
"For me (the second time) it's a controversial point because I'm not sure if - I don't know which decision was right. But, honestly, I didn't have any intention to throw the racket. I slid.
"Honestly, I thought that I will fall forward. Maybe it did look like I threw the racket. I don't know. I didn't see any videos yet."
The Russian maintained that Azemar Engzell had come to the wrong decision, saying: "For me, she didn't do a right decision. Yes, that's why I didn't want to shake hands with her."
Despite the nature of her defeat, Andreeva, who reached the third round at the French Open last month in her first Grand Slam main draw appearance, stressed that there were positives to take from her run at her first senior grasscourt tournament.
"Obviously it's my first time on grass. I kind of didn't expect to go that far in Wimbledon because first time on grass, I had no experience at all. I passed qualifiers. It gave me a lot of confidence," Andreeva said.
"It's a good experience for me, for sure. I hope that next year I will do better here. We will see if I really can...
"After this tournament I will take some days off just to relax and not to play tennis. I don't want to play tennis for a few days, for sure. After I will be back on clay and I will play Lausanne, WTA 250. Then I think I'll play US Open."
