The Dutch international scored the opener in his side’s 1-1 draw with Fiorentina on Sunday night, before Slovenian international Josip Ilicic equalised 20 minutes into the second period to deny the hosts all three points.
The draw leaves Milan sixth in the Serie A standings, and having missed out on European football after their dismal eighth-place finish last season, De Jong is adamant to lead his side back into the Champions League next year.
"Fiorentina only had one chance and they scored a nice goal,” he told his club’s official website. “We were a bit tired and we’re taking home just one point. This is football, but our objective remains to finish in the top three.
"We have another match on Wednesday and we want to pick up the three points. We have to win against Cagliari to remain on track and reach our objective. It won’t be easy, but we have to always believe."
The 29-year-old reinforcer revealed his pleasure working under new coach and former Milan icon Filippo Inzaghi.
"The coach has done a good job with us, he’s always very positive,” De Jong said of the young manager. “We believe and we never give up, just like our fans. We do this for our fans and for the club, which is very important.”
Milan face Cagliari in their midweek fixture on Wednesday before hosting Palermo on Sunday night.