The US has deplored Turkey's redeployment of a research vessel to the eastern Mediterranean and accused it of intimidation.
State Department spokeswoman Morgan Ortagus said the move would damage efforts to resolve Turkey's maritime dispute with Greece.
"Turkey’s announcement unilaterally raises tensions in the region and deliberately complicates the resumption of crucial exploratory talks between our Nato allies Greece and Turkey," she said.
"Coercion, threats, intimidation, and military activity will not resolve tensions in the eastern Mediterranean. We urge Turkey to end this calculated provocation and immediately begin exploratory talks with Greece. Unilateral actions cannot build trust and will not produce enduring solutions."
In August, Turkey sent a survey ship and naval escort into contested waters, alarming both Cyprus and Greece, which in turn began military drills. On Monday, Turkey announced the seismic research ship Oruc Reis would return to the eastern Mediterranean despite warnings of EU sanctions.
Ankara has rejected criticism of its exploratory activities and said it was operating on the Turkish continental shelf.
Germany also urged Turkey to end “provocative acts” in the region and said the redeployment of the ship was a major setback to efforts to ease tensions with Greece and Cyprus.
German Foreign Minister Heiko Maas, speaking before a visit to Greece and Cyprus, said Turkey must show an interest in diplomatic talks over disputed maritime boundaries.
"If there should be renewed Turkish gas exploration in the more controversial sea areas in the eastern Mediterranean, this would be a serious setback for efforts to de-escalate," Mr Maas said.
"Ankara must end the cycle of detente and provocation if the government is interested in talks.”
He said Germany backed Greece and Cyprus in the dispute and called on Turkey to ensure dialogue with Athens was not hampered by unilateral measures.
Mr Maas dropped a visit to Ankara from his itinerary because of the situation.
"My decision only to travel to Nicosia and Athens today is owing to the current developments that we have been talking about," he said.
Talks on resolving the situation will take place at an EU summit this week.
Greece said Turkey’s move on Monday was illegal and accused Ankara of stoking tensions in the wider region.
It also said it would not hold talks with Turkey until the ship is withdrawn.
Greece "will not sit at the table for exploratory talks while the Oruc Reis and escorting warships are out there", Minister of State George Gerapetritis told Parapolitika radio.
Ankara and Athens this month agreed to set up a system to prevent military conflict, including a hotline to avoid accidents in the sea and air.
The two governments also signalled their intention to resume exploratory talks aimed at building confidence and resolving disputes last held in 2016.