The 23-year-old Belgium international was substituted 17 minutes into the Champions League quarterfinal second leg against Paris Saint-Germain at Stamford Bridge.
The Belgium international was replaced and walked straight down the tunnel for treatment after struggling with the injury in the opening exchanges, with Andre Schurrle coming on in his place.
But he has told Canal Plus that he went off as a precaution: "I already felt some pain in my calf during the warmup. I didn't want to take a risk."
In his post-match press conference, Jose Mourinho confirmed the calf injury and speculated that Hazard would need a couple of weeks to recover, although the winger had yet to be assessed.
Schurrle scored the Blues' first goal on the night, before Demba Ba's late strike clinched a 2-0 victory and progression to the semifinals on away goals after the tie ended 3-3 on aggregate.
Hazard has been in scintillating form for the Blues this season, scoring 14 goals in 33 Premier League appearances.
He recently hinted at a possible summer move to Laurent Blanc's PSG side, stating: "If my wife tells me to go to Paris then I'll have to take this into consideration."