Almost one million Deutsche Telekom clients were knocked offline from Sunday, with Germany's online security chief describing it as "a hacking attack".
Merkel said she did not know who was behind the strike, but added that "such cyber attacks, or hybrid conflicts as they are known in Russian doctrine, are now part of daily life and we must learn to cope with them".
"We have to inform people, and express our political convictions clearly," she said, calling on the population to "not allow themselves to be irritated" by such rogue operations.
"You just have to know that there's such a thing and learn to live with it," she told journalists.
Merkel had said earlier this month that attacks orchestrated by Russia "could also play a role" in Germany's election campaign next year.
The warning was echoed by the head of foreign intelligence service on Tuesday.
"Europe is in the focus of these disturbances, and Germany particularly so," foreign intelligence service chief Bruno Kahl told the Sueddeutsche Zeitung daily in an interview.
There are indications that "cyber attacks are taking place with no reason other than to sow political uncertainty," said Kahl.
Germany's biggest telecommunications group Deutsche Telekom became the latest victim of an online assault that lasted over a day from Sunday.
"It was quickly clear to us that it was a hacking attack," Arne Schönbohm, the head of the Federal Office for Information Security, told the regional newspaper group Funke.
"That is organised crime," he said, adding that the hackers apparently used the so-called Mirai malware to infect routers, preventing them from connecting to the main network.
The attack could have caused far more destruction, Schönbohm told Die Welt daily.
"We were lucky this time -- the attack didn't work properly," he said.
While it managed to force the targeted router offline, the malware failed to install properly and was destroyed when the router was rebooted.
Tagesspiegel daily, quoting unnamed security sources, drew a link between Sunday's event and Russia.
Mirai was developed by the Russian hacking group Sofacy, which had targeted the German parliament in 2015, the newspaper said, adding that the telecoms assault could be a dry-run ahead of a wider attack when Germany hosts the G20 summit next July.
Russia has been blamed for several major hacking operations, with Washington last month formally accusing Moscow of trying to "interfere" in the 2016 White House race with online attacks hitting US political institutions.
With Germany also gearing up for a general election expected next September, top politicians are wary that it could also fall prey to similar rogue operations.
Merkel had said that "we are already, even now, having to deal with information out of Russia or with internet attacks that are of Russian origin or with news which sows false information."
Germany has suffered repeated cyber assaults in recent years.
In September, several political parties were sent fake emails purporting to be from NATO headquarters but which in fact contained a link that installed spying software on victims' computers.
The emails affected party operations such as the regional network of the Christian Democratic Union in a western state, and the federal offices of the Left party.
The German parliament also fell victim to a 2015 attack that security services have since blamed on Russia.
That rogue operation against the Bundestag involved an aggressive attack by Sofacy that had also struck NATO members and put French TV station TV5Monde off air.
Amid the rising frequency of attacks, Germany's defence ministry this year set up a cyber department to coordinate a response to online intrusions.