Regional, s-bahn services and long distance trains are back on track, the rail operator said, but after being out of service for more than three days, there were still backups and delays in its freight services.
GDL president Claus Weselsky said on Monday that he thinks his organization can reach an agreement with Deutsche Bahn by Christmas.
"Surely, an agreement is possible if we could finally speak about the issues," he told ZDF's morgenmagazin.
Both sides have agreed to continue negotiations.
"During the day, we'll be talking to the head of the parliamentary committee and I hope that we can find a time to talk," said GDL regional chief of Berlin, Saxony and Brandenberg Frank Nachtigall on radioeins Monday morning.
He also warned that should there be no agreement, there will be further strikes.
"That our demands are fully met, no one actually thinks that will happen - the GDL is no stranger to the world. But if (Deutsche Bahn) also doesn't yield to a middle ground, the GDL will make the only stand available to us: We'll strike," he said.
The readiness to negotiate is clearly the new line of the union. Weselsky also said: "They know that we are willing to compromise. When we demand five percent, no one thinks - not even the chiefs - that we'll get five percent."
The latest strike ended early, on Saturday, though train service the day after it was called off was still heavily disrupted, with only 60 percent of scheduled trains on the tracks. The strike was originally called to run until early Monday morning.
The union is demanding a five percent pay raise, a shorter work week and the ability to represent all on-board personnel, as well as the train drivers.