Even so, "we have to fight for our own future ourselves", she said.
She described the summit as a wake-up call, adding: "The times in which we can fully count on others are somewhat over, as I have experienced in the past few days".
Clearly disappointed with Mr. Trump's positions on NATO, Russia, climate change and trade, Ms. Merkel said in Munich on Sunday that traditional alliances were no longer as steadfast as they once were and that Europe should pay more attention to its own interests "and really take our fate into our own hands".
Trump - who returned from his nine-day worldwide trip on Saturday - had a different take.
The BBC's Damien McGuinness, in Berlin, says the comments are a sign of growing assertiveness within the EU.
After returning to the U.S., Trump on Sunday tweeted that the nine-day trip "was a great success for America".
Mr Trump said he would abandon the Paris deal - the world's first comprehensive climate agreement requiring countries to cut carbon emission - during his election campaign and has also expressed doubts about climate change.
Mrs Merkel called the climate talks "very hard, if not to say, very unsatisfactory".
Saying she'll stand up for the European Union project of "peace and freedom", Merkel singled out this month's victory of Emmanuel Macron over nationalist Marine Le Pen in France's presidential race.
Jared Kushner Senior Advisor to President Trump after arriving in Baghdad Iraq
The G7 summit was part of Mr Trump's first foreign trip as president, during which he repeated past criticism of North Atlantic Treaty Organisation allies for failing to meet the alliance's military spending commitment of 2% of GDP.
It might have been thanks to the beer, pretzels and Bavarian brass-band enlivening the crowd.
"That weakens America and irritates its partners", said Hardt, the foreign policy expert in parliament for Merkel's conservative Christian Democrats.
"Those of you who have reported on the chancellor for a long time will know how important German-American relations are to her", he told the news conference.
On Sunday, the chancellor of Germany, the most influential leader in the European Union, said that Europe can not completely depend on its allies and must take control of its own fate, clearly referring to the US. Yes, it's a tough call: it's either whoever the leader of Italy is this week, plus whichever socialist is temporarily in charge of France, plus the your-name-her chinless wonder domiciled at 10 Downing Street in London. Check back for updates or follow BuzzFeed News on Twitter.
She might not have welcomed Brexit or Trump.
Merkel's comments were similar to some she made shortly after Trump's November election.