The midfielder, 34, played a key role in Madrid's title win this month, finding his best form in the second half of the campaign.
"The only sure thing is that I'll play for Madrid until June 2021," Modric told Croatian newspaper Sportske Novosti. "I haven't spoken [to the club] yet and there's no hurry. When the time comes, we'll meet and clarify our plans to see what we'll do. There's no stress. Right now the most important thing is the focus on Real Madrid and then on Euro 2020.
Modric said that he'd like to retire at the Bernabeu but is aware that the club will have the final decision.
"Who wouldn't [want to retire at Madrid]?" he said. "But it remains to be seen if the club want that. Real Madrid is my home, but Madrid decide what's best for the club. I know that midfielders don't often stay here until they're 35."
"If Madrid believe I'm no longer the right man, I'm ready for that," he added. "It wouldn't change my feelings for the club. But despite that I hope to break that 'rule'. I worked hard to come to Real, I've been through everything and I'm not going to give it up easily. I'll fight on the pitch to deserve to stay."
Madrid secured the title -- the first time they've won La Liga since 2017 -- with a run of 10 consecutive victories, overhauling rivals Barcelona who were two points clear when competition restarted.
"I've won 16 trophies at Madrid, four Champions Leagues, but this trophy made me especially happy," Modric said. "We should have more domestic trophies because we didn't play as well in some seasons... In totally different conditions, without fans and in a smaller stadium, we did really well. We were really solid."
Modric received some criticism in his first season at Real Madrid in 2012-13, and says he understands why another Premier League recruit, Eden Hazard, has found life difficult this campaign.
"Eden is a great player. He hasn't had any luck with injuries since he came," he said. "It was obvious how desperate he was to play and show what he could do. I've been through those moments of high expectations and the process of adaptation, so I told him to be patient. If he's ready for Manchester City, great, if not the most important thing is that he's totally fit for the start of the new season in September."
Hazard -- who missed much of the season with a series of ankle problems -- was intended to help fill the void left by the departure of Cristiano Ronaldo in 2018.
"We don't have to debate how important Cristiano was for Madrid," Modric added. "But I must say that the fact that he isn't here doesn't worry us, in the sense of not being able to have the same ambitions. We were convinced that we could keep winning without him because, independently of the strength of individuals, the team always comes first."