The Italian official told a parliamentary meeting the EU was in a position to bring both military and diplomatic pressure to bear in helping to tackle problems.
She said, "Our hard power should not be neglected but, on its own, hard power usually does not go far enough.
"What the EU has though is a unique mix of hard power coupled with carefully tailored diplomatic measures. This is the unique European way and we should not give up on this."
Mogherini was speaking in a debate with members of the foreign affairs committee on Tuesday.
She also conceded that Europe needs to beef up cooperation on defence matters, but also cautioned that this should not undermine the work being done by Nato.
This was taken by some as an indirect reference to plans for a European Defence Union (EDU), or 'European army' as it has been dubbed.
Some MEPs, including UK Tory Geoffrey Van Orden, have come out against the idea of the EDU, warning that it could duplicate operations undertaken by Nato.
Speaking recently, he said, "We should be under no illusions - the ayatollahs of European integration see Britain's departure from the EU as their great opportunity. We will no longer be there to put a brake on their ambitions. This is particularly true of defence where France, in particular, has long sought to lead an EU army that excludes American influence from Europe.
"This is very dangerous in today's challenging world. An EU army has no credibility with our potential enemies."
But Mogherini sought to counter such arguments and made a point of telling MEPs that her desire to see stronger defence cooperation between member states should "go hand in hand" with Nato.
She said, "That is not to say that Nato and the EU are no different in nature because they are. Nato is a military alliance while the EU, of course, is not.
"But the debate about autonomy is something of a false dilemma because it is obvious that Nato and the EU are very different."
She added, "Yes, we need to strengthen EU cooperation on defence but let's not overlap what Nato is doing."
Mogherini, who was speaking in a debate on the EU global strategy, also urged "better and more efficient" spending on defence, citing the example of European 'battlegroups.'
A battlegroup is a military unit adhering to the Common Security and Defence Policy (CSDP) of the EU.
"We have the battlegroups and it is time we used them," she said.
She told the packed meeting that when it comes to defence the EU had to become a "stronger security provider" and more of a "global player."