Williams, 21, was in strong form for Athletic during the 2023-24 campaign, making 39 appearances in all competitions, scoring eight goals and registering 19 assists in the process.
The forward has also impressed for Spain at Euro 2024, playing a key role in Luis de la Fuente's side breezing into the knockout round of the competition with three wins from three Group B fixtures.
Williams penned a new deal at San Mames towards the end of last year, but there is thought to be a release clause of around €55m (£47m) in the agreement.
Arsenal and Liverpool are being heavily linked with the attacker, while Barcelona are also believed to be determined to secure his signature during the summer transfer window.
Barcelona, Liverpool, Arsenal 'are all keen on Williams'
A recent report claimed that Williams is determined to move to Barcelona and will reject interest from elsewhere in order to secure a switch to Camp Nou.
The forward has welcomed reports of interest from major teams, including Barcelona, but he has insisted that a decision on his future will not be made until after Euro 2024.
Spain are currently preparing to tackle Georgia in the last-16 stage of the competition on Sunday evening, and Williams is set to come back into the XI after being rested against Albania last time out.
"Everything that comes from outside is good, it means I'm doing my job well. Every kid dreams of being noticed by big clubs," he told La Vanguardia.
Williams has impressed for Spain at Euro 2024
"I'm focused on doing well at the European Championship, and whatever comes after that I'll find out because these days I'm totally disconnected."
Williams also opened up on his relationship with Spain teammate Lamine Yamal, who starred for Barcelona's first team during the 2023-24 campaign at the age of 16.
"We get along very well. We're not just teammates, we're also friends, and I think that's something that also matters when it comes to leading a team to the big time," he said.
"[Alejandro] Balde (Barcelona defender) is the reason, he was the link between us. The first time we met, Lamine joined Balde and me and after that, we started talking and we saw that we had a lot of similar topics of conversation. That's also when the banter started and now I think we have a nice relationship."
Williams has represented Athletic on 122 occasions since breaking into the first team in 2021, scoring 20 goals and registering 26 assists in the process.