The 25-year-old has been linked with replacing Kimi Raikkonen at the Italian team from 2016 onwards.
However, Bottas - in his third season at Williams - says he is thinking only about helping his current team challenge for victories.
"Once you're in the car you don't think about any speculation," he said.
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"There is nothing in your mind other than driving, but out of the car of course it is disturbing when there are some rumours."
Mercedes have been in dominant form through the first half of 2015.
Reigning world champion Lewis Hamilton has won five of the 10 races so far, with his team-mate Nico Rosberg winning three.
However, Ferrari's Sebastian Vettel picked up his second win of the year in Hungary last time out, giving Bottas the belief that Mercedes can be toppled.
"Mercedes are really strong at the moment but Ferrari showed in Budapest that it is possible to beat them," he said.
"Never say never, we are still aiming to win races. They have a really quick car but anything can happen in motorsport.
"We need to believe in it and take every opportunity - it could be there this season."
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Valtteri Bottas says speculation about a move to Ferrari is "disturbing" as he looks to focus on winning his first grand prix with Williams.