"I would lump any of these into the provocative nature in which Iran has operated on the world stage for a number of years," he added.
When asked what Washington wanted from the much-anticipated talks, Mr Gibbs said: "They can agree to immediate unfettered access [of the nuclear fuel facility]... That would be the least that they could do."
France also called the tests a "provocation" and called on Tehran to immediately stop "these deeply destabilising activities".
British Foreign Secretary David Miliband called the tests "reprehensible" but said they should not distract attention from the talks.
EU foreign policy chief, Javier Solana, said Tehran had produced "a new context" for the talks, but said the time was not right to discuss further sanctions.
Russia's Foreign Minister Sergei Lavrov called the tests "worrisome", but called for restraint.
"Now is not the time to succumb to emotions, it is necessary to calm down and above all to start up an effective negotiation process," Russia's foreign ministry was quoted as saying.
Gesture of defiance
Iran's foreign ministry spokesman Hassan Qashqavi said the missile tests were merely part of an annual military drill, and were not a reaction to the nuclear crisis.
Iran's president Ahmadinejad has repeatedly predicted Israel's downfall
The Shahab-3 (Meteor-3) is classed as a medium range ballistic missile but is the longest-range rocket Iran has successfully tested in public.
Iran says the missile, which it first tested in July 2008, can fly some 2,000km, although Western defence experts have put the strike range at 1,300km (807 miles).
The surface-to-surface Sajjil is a new, two-stage missile using solid fuel, which is considered to give a more accurate delivery than liquid fuel rockets. It has been tested by Iran twice, in November 2008 and May 2009.
The BBC's Tehran correspondent Jon Leyne says Iran's enemies might be most worried by the test-firing of the Sajjil missile. It is more advanced, and multiple stage rockets offer the potential for longer ranges, he says.
The Shahab-3 and Sajjil rockets are currently believed to be capable of reaching not only Israel and US bases in the Gulf, but also parts of Europe.
On Sunday, the medium-range Shahab-1 and 2 missiles with a range of 300 to 700km (186 to 434 miles) were tested.
The short-range Tondar-69 and Fateh-110 type, with a range of up to 170km (100 miles), were also tested.
Tehran says the Qom plant is open for inspection by UN experts
Although the tests are likely to have been planned in advance, Iran will not be unhappy if they are seen as a gesture of defiance by the West, our correspondent adds.
Iran is under increasing pressure to co-operate fully over its nuclear ambitions - particularly since the revelation of a previously undisclosed uranium enrichment plant.
President Mahmoud Ahmadinejad has insisted that the plant, near the holy city of Qom, does not breach UN regulations and says it is open for inspection by UN experts.
But leaders of the US, Britain and France accuse Tehran of keeping the plant secret in breach of UN rules.
They have raised the prospect of new, tougher sanctions against Iran if Thursday's meeting with the so-called P5+1 (US, UK, France, China, Russia and Germany) yields little progress.
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