A run of four wins on the trot has lifted the Rossoneri to eighth in the standings but Milan are five points behind city rivals Inter Milan, who are fifth and hold the last UEFA Europa League qualifying spot with five games remaining.
"We have to play every game with the same intensity," Seedorf said to www.acmilan.com. "We cannot take anything for granted. We have to maintain the same fighting spirit and hope that other teams drop points along the way."
Riccardo Montolivo's solitary goal handed Milan a 1-0 triumph over Catania on Sunday night.
"The important thing is to achieve results," Seedorf said. "Results are what matters because no-one remembers good performances when you lose. My team showed great determination against Catania and understood the importance of getting a win."
Milan have shown plenty of improvement at both ends of the pitch in recent weeks, scoring eight goals while giving away just one in their past four games.
"We are going through a positive spell," Seedorf said. "But it's precisely in situations like this one when it can happen that you relax a little bit. We simply cannot afford to do that."
Milan host Livorno on Saturday before travelling to the Stadio Olimpico to face Scudetto contenders Roma on 25 April.